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Hit and miss key strokes And double blows of the hammers

"Hit and miss" is an expression which comes from old gasoline engines which would fire only once every few RPMs when the governor let them. Your audience might not be very patient with this arrangement on your piano. It is pretty hard to play a two part invention when the hammers only hit about once out of every five key strokes. So, here is your solution...

Look at the diagram of the hammer and jack assembly carefully.

Notice the position of the jack at rest. It should be tucked under the round back side of the hammer butt. When you strike a key, the jack carries the thrust of the blow upward, and it sends the hammer flying forward.

Try this on a key that works right and watch the action. The back end of the jack is supposed to catch the round "regulating" button with the screw in it and the jack flips back out of the way. This lets the hammer catch on the back check, the brake shoe device with the rectangular piece of felt. This also allows the hammer to be ready to be struck again after a sustain.

You can see all the parts involved in the diagram for Uprights.

Well, if the action is a bit old and worn, the round button will not throw the jack out of the way far enough. The result is that the hammer hits the jack as it bounces backward, and the hammer flies back forward again hitting the string a second time. I call this the "ba-bang syndrome."

We need to get that jack to tip back out from under the hammer butt when you hit and hold the key down. Before going any further, look up Adjusting lost motion in the Table of Contents, and do that first. It is very common to find all your action problems disappear when the lost motion is gone. If the adjustment to remove lost motion fails to get rid of the "ba-bang syndrome," go on to adjust the jack buttons as instructed below.

Also, before proceeding, check the wood rail, with all the wooden adjustment nuts mounted on it, right above the jack butts (as in A and B below). This wood rail is held on with four or five screws which are a bit hard to find. If the rail is loose or dropping back? Push it forward into place, make sure the metal tabs are UNDER the screws, and tighten the screws. This could be all your problem with weird hammer movement. If not, proceed...

This adjustment is just as easy as removing lost motion, but first you will have to get a tool. There are two kinds of buttons, and you may be able to make the tool for the button you have:  Of course, the ideal would be to purchase the tool from out Catalog.

A. Loop top adjustment screw:

This button is the most common and the hardest to improvise a tool for. The best thing is a biggish shanked screw driver. Cut the bit off with a Dremel tool, or saw it off. Then cut a slot in the end of the shank wide enough to fit over the loop top. Make sure there is a little slop so that it doesn't bind up. If it fits too tight into the piano action, grind the shank down to a smaller diameter with a grinding wheel.  Again, you would do better to purchase our tool for this one from our online Parts Catalog.

B. Tab end adjustment screw:

Use the same method, but use a smaller screw driver, and cut a slot much narrower, again, leaving just a little bit of slop to prevent binding.  This tool will slip over the tab and work pretty good.

Now sneak up on the jack that is offending. Slip your regulating tool down through the action and over the top of the screw in the "jack button," and give it a half turn clockwise. On an old piano you should work the wooden nut loose by turning it back and forth, slowly loosening it to avoid breaking it. If you turn it all at once it could break off, and the result is that you can not adjust at all. Make the adjustment suggested above, that is, screw the jack button down until the top end of the jack has about 1/8 inch open space between the jack and the hammer butt with the key depressed and held down. Too little space will allow the problem to persists, and too much space will reduce the force of the jack pushing the hammer butt resulting in a quiet note.

IF YOU BREAK OFF A JACK BUTTON SCREW:   My supplier has come out with a repair part is you do break off the jack button regulating screw.  It is a genius little thing.  ON THE ACTION PARTS PAGE, look for part number 24476.

With the tool removed, strike the key, and hold it down. Does the jack now jerk out from under the hammer butt after thrusting? Is there about one sixteenth to one eighth of an inch between the top of the jack and the hammer butt when you strike and hold down the key? If so, don't adjust any further. If not give it another half turn clockwise.

Do this to all the keys that have the "ba-bang syndrome." Even adjust those that seem to be trying to do it.



Kimball used brass jack springs in their actions in the past on console pianos. The brass gets brittle and the spring collapses. This will result in the jack failing to reset, and you will hit a blow, and you cannot repeat the blow for a while.

You need to replace the jack springs. Open the piano until the action is fully exposed and check.

Diagrams of actions

Order jack springs

Reamer to clean the old glue out of the bottom hole in the wippen.

If, after a couple of turns, the jack is still hanging up under the hammer butt, you may have overly worn back check felts which are not catching the stump of the hammer butt and buck skin there. Carefully bend the back check forward a little bit, supporting the whippen with one hand. The safest way to bend the back check wire is with two pliers. NEVER do this first. It is an act of desperation where actions are very worn. If the back check felt piece is worn very thin, you can order a set from me. DO NOT improvise at this point. Find Back check repair in the Table of Contents for instructions.

There is a piece of buckskin on the hammer stump which catches on the back check. Compare the center of the piano with the extreme ends. Are the buckskins in the middle worn very thin or completely missing? If so, you should replace them with real buckskin from our Catalog in the Felt Parts section. The back checks are not grabbing well if they are catching on the wood where buck skin has worn away. To make the repair, see the Table of Contents for Buckskin Replacement.

As always, if you have done all these steps and the hammers still hit double blows, ba-bang, your tuner must take over since the problem is too tricky for must folks. But do have a peek into the very heart of the action for junk hung up between parts.

Hit and miss hammer blows:

Sometimes the hammer plays, and other times it feels like the action let your key stroke miss the target. This could simply be caused by humidity. Refer back to Section A. and loosening key felts.

However; Your problem could be that the jack is not tucking back under the hammer when the key is up and at rest. First, check the coil spring under the butt of the jack. Is it out of its upper recess? If so, put it back. If it is broken you need to order a dozen and replace any suspect springs. We sell these in the Action Parts area of the Catalog.

Next, pull the jack back, and let it return forward. If it is sluggish, the jack spring may be broken or weak. Replace it. I have seen improvising here, but it better be very much like the original to work right. You can order jack springs from me. They are cheap. To make the repair, see the Table of Contents for Replacing jack springs.

If the spring seems OK, and the adjustment is right, you may have a jack which has tightened at the pin hinge point. Spray it with aerosol silicone, which you can buy at any hardware store. Hit the hinge point of the hammer while you are at it. If this loosens the jack, do all of the jacks and hammer butt hinge points.

If you have a Kimball or other console with brass springs, you should replace them all. They were a disaster and will cause trouble forever. You can order jack springs from me.

Jack came loose:

When you look into the trouble spot, do you see that the jack has come out of its mounting point in the whippen? Is it even missing? Look into the action, and you may see that it has fallen into the works. See the Table of Contents for "Replacing a loose jack."


After you have done all the above, is there still a problem? Before you call the tuner, eyeball the line of parts along the action. Does the offending part look like it is slightly forward throughout the whole serious of parts for that note. If so, look at the key levers to see if the offending key lever is higher or lower than the rest? If so, there may be junk under the key levers. Go back to Section A of this chapter and open your piano clear up, and remove the keys. You will very likely find junk under the keys holding some of them up too high.



F. Limber Neck OR, Floppy Hammers