A question of liability

[A440A@AOL.COM]

 >My question is this:  to what degree am I liable if it was caused by
>their piano and their casters, and all I did was roll it out from the
>wall. 

Greetings, 
    It seems that you damaged their floor, and regardless of what you used to 
do it with,(their piano, your tilter, tar on your shoe, dropping a tool, etc) 
 the liability is, IMHO, yours.  If you were carrying their piano out, (say 
to your shop), and  tore a door frame off,  that wouldn't be their 
liability....( don't ask me how I know). 
     A full size upright can weigh 600 lbs, and the majority is on the back 
two casters. 
Usually, two strips of galvanized tin are sufficient to allow damage-free 
rolling of uprights out from walls. 
Regards, 
Ed Foote RPT