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!