https://youtu.be/pgEsYQgooLw
- In this video, I observed and noticed that there is an obstruction between 'the jack of 'the wippen upright piano' and itself 'the let-off.' It could be a small object like a child's toy, a stud, or a pen. We need to inspect the 'upright piano action' to determine what caused this issue. When pressing the keys (G5, A5), we can see that it's strikes the strings properly, but the keys (B5, H5) are not functioning. Why?
There are three possible causes:
1 If a foreign object has dropped into the 'upright piano action,' it needs to be removed. You can use various tools such as a screwdriver, a hook, or pliers.
2 The suede material from the 'hammer butt buckskin' in the 'action' of the upright piano may have become unglued. This can obstruct and prevent the keys (B5 and H5) from functioning.
3 It is also possible that one of 'the jacks' (B5) has become loose from the gap in the 'wippen.' This causes 'the hammer' to be stuck and obstructs the movement, affecting 'the key' (H5) as well.
Based on my analysis it's video, I believe the reason for the detached 'jack' from the 'wippen' is the most likely cause there. Here is an instruction on how to fix it yourself:
Instruction for repairing the loose jack flange:
1 Remove 'the 'action' from the upright piano. Disconnect any pedal rods from 'the action.' Locate the screws or nuts that hold the action brackets to the piano's plate. Remove these fasteners, tilt the top of the action towards you, and lift the action out of the piano by gripping 'the hammer rest rail'.
2 Identify 'the whippen' that has the loose 'the jack flange'.
3 Disconnect 'the bridle strap' of that particular note from the 'bridle wire' on the 'whippen.'
4 From the back of 'the action', remove the screw holding 'the whippen flange' and take out 'the whippen.'
5 Clean any loose glue or debris from 'the jack flange' and 'the whippen', and ensure a proper fit. Apply a drop of PVA glue' to the whippen' where 'the jack flange' will be attached. Ensure that 'the jack flange' is aligned at a 90-degree angle to 'the whippen', and there is enough glue with some excess squeezing out. Allow the glue to set for a few minutes and remove any excess.
6 Reinstalling 'the whippen' can be challenging. Make sure 'the jack spring' is properly seated in 'the whippen' and jack. Pivot 'the jack' against 'the spring' to position it against 'the hammer butt leathe'r while aligning 'the whippen flang'e with 'the whippen rail'. It may be necessary to have 'the whippen flange screw' already in place due to interference with 'the damper spoon'. Attach 'the whippen flange' to 'the rail' using the screw.
7 Keep 'the whippen' raised in its normal position until 'the bridle strap' is reattached to 'the bridle wire' to prevent 'the jack' from jamming on the hammer. In many pianos, 'the bridle strap' threads through a hole on 'the hammer butt backstop'.
8 Verify the proper operation of the repaired note.
9 Reinstall 'the action' in the upright piano. There are several studs in the upright piano on which the action brackets rest—one stud for each bracket. Hold the action by 'the hammer rest rail' and tilt the top of the action towards you. Position the action brackets onto the studs, and you can judge the proper alignment by observing how 'the whippens rest' on 'the capstans of the keys'. Once the action brackets are resting on the studs, tilt the top of the action towards the piano's plate. Attach the action to the plate using screws or bolts. Reinstall or reposition any pedal rods.