Wax Removal/dead strings

[Phil Ryan]

I had about 25 bass strings go dead (25 lowest) on a rather new Yamaha 
C1 (15 y/o) in a lounge.  I diagnosed it as someone spilling water into 
the piano as there was no evident stain, discoloration, crack visible 
and recommended replacing them..  Hearing everyone recommending 
"washing" the wax off of bass strings (etc), I am wondering if  my 
diagnosis was incorrect.  What could cause 25 bass strings to go really 
dead with no apparent cause? 

Phil Ryan
Miami Beach