Urgent need of help with three technical terms

[A440A at aol.com]

I wrote:
<< "deviation from parallel".

Andreas writes; 

So that is the technical term for it? >>

   That is what seems to be a technical description, but as far as a "term" 
for this condition, I don't know. 

>>However, in a badly balanced action (if the measurement I’m asking for 

is too small or even negative) a heavy hammer would out-balance the butt and 

the back stop and it would tend to tip forward. I forgot to indicate that I 

was referring to a problem case where the action rail might be too far from 

the strings.<< 

    I see, in a badly balanced action anything is possible. What the 
difference is,here, is that a large hammer will have a center of gravity that is 
closer to the strings, so yes, it would return slower. However, if the smaller 
hammer were to share the same center of gravity,(which would require it to be 
closer to the strings than the larger hammer), their return speed would be the 
same,(minus any mass/friction relationship differences). 
Regards,  
Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html