I'm currently working on my 1930s upright piano, renewing bridal tapes, and reshaping hammer felts. (Had the piano tuner round the other day to remove the action so I can work on it over the next few weeks).

Noticed before removing the action that the hammers do not return quickly if at all if the bridal tapes are broken or not connected. (notably when playing hammers return slowly and playing the same note 3 times in a second / 180bpm and the middle note is hardly audible. I think the inevitable bounce off the string and the slight offset of balance is mainly what had been returning the hammers) All but 1 of the hammer springs are still hooked onto the loop cords.

Is this right, or should I also be renewing all the hammer springs too? The piano tuner said that if they were too powerful the touch would be altered, which makes sense, but just how powerful should they be?

Action is labelled 'Herberger Brooks ltd, London'