I had a similar problem with my Big Buddy and after reading volumes of web info I decided to print the pdf schematic from the Mr. Heater site and grab a phillips screwdriver and set of wrenchs. I don’t buy every new power tool that comes on the market so it probably took me longer (~ 3 hrs) but I was able to disassemble, blow out all gas lines with air compressor and upon reassembly it’s working better then the day I brought it home…. Lost a few pounds of knuckle flesh but saved me the inconvenience of sending it in and being without a heater. Plus it gave me something to do on a sub zero eveing. I also talked with a Mr. Heater tech prior to tear down and he was of the opinion that they are pretty simple and didn’t feel I shouidl fear tearing it apart. The Mr. Heater webiste has 4 or 5 service centers in the Twin Cities (sorry not sure where you are from).
http://www.mrheater.com/
Good luck. If you get stuck let me know and I’ll try to help. Kurt
PS – You should definitely install the $9 Mr. Heater filter if using anything other then 1 lb bottles. As the larger tanks age they rust and sooner or later your WILL have plugged lines.