When I had problems with mine, there was 2 things... . There are 2 solonoids underneath that are the "gas valves. " They had gotten so hot they had actually started melting. When that happened, under the back cover, there is a little white thing that is a fuse. That fuse had blown. My local repair guy had them in stock and if I remember right the fix was about $50. (this was 3 years ago, and it's 6am... i'm a little fuzzy)
Mine was a PITA to take appart, the whole front plate had to come off. My drum just hung out there with no support while I worked on it.
JP