- Sometimes we can observe that after the hammer of the upright piano strikes the string, it returns very slowly to a static position to the hammer rail there.
Why is this happening?
Most often this is due to very tight fitting 'the butt hole of hammer' to 'the hammer butt flange'. Perhaps this pin is too large in relation to 'the butt hole of hammer' too. Either 'the hammer butt' itself swells there. There is an increase in friction between the pin and the wooden place 'butt hammer hole' there. As a consequence, the defective kinematics of whole hammer there.
What we can do?
The script to fix is:
1 Sometimes you can try to put a drop of denatured alcohol on the edges of both bushes (hammer flange). This can be done using a regular medical syringe there. Try make it without remove the hammer from upright piano action.
2 If after the injection of alcohol, the hammer still does not return well to 'the hammer rail', then you need to remove the hammer from the upright piano action.
3 "gently" you need to loosen the hammer in the flange. With one (right hand) we tightly squeezes 'the hammer flange', with his left hand holds the hammer (in the place of the butt) and gently swing it from side to side. It usually helps here.
Warning: there is a chance when performing step (3) to break the wooden 'hammer butt flange'.
Less often, it may be that a strip of skin has come off from 'the hammer butt',
or 'the capstan' of the keys is too high and it rests on the hammer butt'.
Or a foreign object has gotten between the moving part of 'the hammer butt' and 'the hammer flange' there too. This could be the reason there too.
And more 'the hammer spring' is broken there or 'the hammer flange loop' is lost there.
https://youtu.be/ncqjj7t3eiA?si=utKM_u1hIy82gSsK
Be careful.
Good luck,
regards, Max