That's probably the next thing to try, as the service manual says a 34 code is a "Lamp Irregularity."
As far as I know, though, the only place to get a ballast is from Mitsubishi, and they can be fussy about selling repair parts like boards to customers. You might try calling their parts department at(NNN) NNN-NNNNand see what kind of mood they're in. Sometimes they will, with the stipulation that there is absolutely no warranty on the part.
Good luck, thanks for using JustAnswer!