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2. Back check repair

Back checks available in our Online Catalog for all types of pianos.
Buy Back Check Felts also.

Before doing this task, remove the Lost Motion from the action so that it does not mess up your adjustments of the back checks. Be sure the Jacks are also adjusted right.


This repair can be done with the action in the piano, or go to Chapter Five to learn how to take the action out of the piano.

This is very simple, and it applies to all styles of pianos. Go to the Diagrams Page to make sure you know what a back check is.  Remove all the back checks felts with a thin bladed knife, sliding it under each felt piece. Scrape most of the old glue off. Use factory made felt pieces which we sell-- See the links at the top of this page. DO NOT improvise with substitute materials in this case.

Before you glue each felt piece on, bend it slightly to match the curve of the wooden back check. Glue the felts on with Elmer's carpenter's glue, and let them dry before reinstalling the action.

After installing the action back in the piano, you may find that some back checks grab the end of the stump or catcher before the hammer can finish striking the string. You will have to bend the back check wire back slightly. You can do this and keep striking the key to test. If you go too far, the back check will not catch at all, or it may grab the stump at a very low drop back point. Slightly bend the wire back forward. You may have to bend the wire so that the back check comes into parallel better with the stump catcher.

Spinets will be a real pain since the adjustment is hard to do through the drop wires. A back ckeck adjusting tool would be very useful in this case.


Grand Pianos:

The process is not very much different for grands as far as the actual replacement procedure. But, you will have to remove the action by using the instructions in Chapter Five.

The problem is that the new back checks may catch the wood molding of the hammer better since the wear is gone. A technician may have bent the back checks forward because of wear, and you will have to bend them back. Do not guess on this. Reinstall the action, and play the keys, both hard blows and soft blows. If a hammer hangs on the back check, and it will not go all the way up and hit the string, then make a note of which key that is. Try to identify all of the notes where the hammer will not freely hit the string.

Remove the action, and slightly bend the back check backward on the offending notes. If you bend one too far, the hammer will hit the string, but it will drop back down too far when you hold the key down after a blow. The hammer may even catch again after dropping way down. The back check on that hammer must be slightly returned forward a bit. You may also improve on the catching activity by bending the back check so that the angle changes and is more parallel with the molding of the hammer. This may have to be done a couple times to get them all right.

Grands often act up in this way after new hammers are installed since the new hammer wood moldings seldom are a perfect match of the originals.


On to task 3.