It's key(G5) of the upright paino won't play when we press repeated it. Why?

[themaximillyan]

It's key(G5) of the upright paino won't play when we press it. Why? It happens only when the key was previously played. How fix it DIY.
If the upright piano hammer isn't striking the strings, it may not be due to 'the capstan of the key' being too low, as the entire 'wippen' would need to be low along with 'the jack' too there. But we don't see it's there. It's possible that:
1'The jack flange' is broken.
2 The pin/screw securing 'the jack to the wippen' has come loose or fallen out.
3 'The jack flange' has detached from 'the wippen'.
4 'The jack spring' has come loose, is damaged, or lost. The spring should push the jack forward.
How to Fix It:
1 If the pin/screw securing 'the jack to the wippen' has come loose or fallen out, you can attempt to reinsert the pin into 'the jack flange's hole' using a screwdriver.
2 If 'the jack spring' has come loose, is damaged, or lost, gently pull the spring upwards to increase its tension. If it's damaged, replace it with a new one.
3 If 'the jack flange' has detached from 'the wippen', you'll need to remove the action from the piano and unscrew 'the wippen' from the action. Then, use PVA glue to reattach 'the jack flange' into the groove of 'the wippen'.
4 You have the option to either glue the broken flange or replace it with a new one.
5 If 'the capstan of the key' being too low that need lightly unscrewing against clockwise from the key.

regards, Max