Weak work 'the jack of wippen' of the upright piano. How fix it DIY.

[themaximillyan]

In the video, we can see that the jack fails to fully lift the hammer after the key (F) is pressed. 'The jack' shifted and it don't hits to 'the  hammer butt' there.
 more cause it's 'the center pin of the jack  shifted from one of the cloth bush 'the hammer flange' there.   OR was unscrewed  'the wippen flange' there. And  'the jack of wippen' work bad.
How fix it:
 Need carefully to press it side use the screwdriver and return 'the center pin' come back.
And other cases which may be solve there:

1 It is possible that (the wippen) spring of the jack, which is responsible for the jack's striking force on the hammer, has become loose. How can you fix it's? You need to slightly stretch this spring to increase its tension. OR change it's to new.

2 The center pin of the jack may be too tight there. How can you fix it's? Try gently wiggling the jack from side to side in this area to the jack is lightly loose there. OR Put down drop oil into bushes the center pin of the jack. (undesair variant).
3 The key's capstan (wood barrel) may be set high there too. How can you fix it's? Attempt to rotate the capstan clockwise by half a turn to down it's.

4 The felt on button of (the let-off) may have become worn down and stiff. You need to lower the let-off button, bringing it closer to the jack's arc. How can you fix it's? Rotate wire hook of (the let-off) clockwise by half a turn. OR need to 'fluff up' the button (let off) use your fingers there.