Total Novice

Hello all, I've been playing pianos for a while but never really done much inside them, though I've always been interested by the mechanism. Our current piano is a Weber-Aeolian w pretty unknown history and age that my father bought about a year ago at most, from a man who had done it up in his garage... Not very well, though. It's all out of regulation; some of the keys barely register the jack on the roller, some of them don't even reach the string before the jack leaves the roller.
Last night I took the action out and fiddled with the top four keys, experimenting with regulating the action, but I have a few questions (please don't laugh if they're simple ) :
a. How does one determine the height to which hammers should be falling on the return? Is it just until they catch against the rest at the back (don't know the technical name)?
b. I know I want the keys to spring to uniform height when pressed. Currently this does not happen. But. I managed to get the hammers for those first four to come to uniform height for any given general pressure- ie, a light, slow touch that just slides the jack past the rollers, a harder slow press that jumps the hammers off the jack, or a regular, fast press- but not for all. At what kind of pressure should I be getting the hammers uniform?
c. What exactly does the top spring (the one attached to a longer silk string) actually do? I know you can adjust its tension but what does this affect? It seemed to me to affect return height but this could have been my imagination!

Thanks in advance for answering very novicey questions. I console myself that everyone has to start somewhere

Cheers,
Jack

Start with purchasing Reblitz's Piano Servicing Tuning & Rebuilding book. Then find a mentor...someone to lean on

All right, I shall certainly at least manage the first part fairly soon... Thanks.