I have the very basic heater control - non digital. The bulb blew a while back and I managed to find out how to access it. I couldn't pull the bulb out and ended up bu breaking it. It appeared to be housed in a small black plastic holder. I pushed this and it went back towards the bulkhead and dropped out of sight. Is it simply a case of a new holder and bulb? My concern is how the holder is to be wired in. Does anyone have part numbers for these?