Okay, I got it. I pulled the burner assembly by lifting the transformer, and sliding the whole assembly out of the chamber. The front end of that assembly looked like someone dipped it in oil and rolled it around in the dirt. I hit it with a wire brush lightly, and burned a lot of the crud off with a torch. A little brake cleaner and a shot with the torch to make sure it wasn't combustible, and re-introduced the whole mess to the burner chamber. Screwed down transformer, and plugged it in. Started chugging like a freight train ( I assume there was a bit of excess oil ) then quieted down and purred away. Ahhh, my garage is warm again! I figure I saved a couple hundred bucks there. Plus I know what to look for when I clean it up this summer.