Somebody told me that Timba Percussion "inherited" Gon Bops.  Just browsing through the latest Drum magazine I found an add, in the "classified" area, that verified was I was told.  Timba is handling Gon Bops repairs and most likely parts too.  Their website is 
http://www.timbapercussion.com and their phone number is (909) 727-8929.  (Their address is 12903 Jurupa Ave.  Fontana, California 92337).  
Depending on what part or repair you need,  sometimes it could be expensive to have done by the official dealer/reparer.  Sometimes there are alternatives that could be cheaper or logistically easier like a "local instrument repairman".  Here in Puerto Rico that is more feasible.  I do not know if you have that in the area you live.
Good luck!  Saludos!