Good point.  I opened the burner up last night and it looks brand new - zero soot or blackening.  Wonder if it was barely used since the vehicle has only 32k on it? I'll look at the fan/bearing very closely.  Even light use would not make up for bearing grease/oil that's hardened with age.  Perhaps I can sneak a lot of oil in there.  I have a device that helps lubricate bearings by pulling the tiny rubber seal back and pressurizing it. Yeah, looking for a quiet motor.....

Looks like a satisfying job and worth it, given that lots of the older, low-tech stuff will outlive the new stuff, if maintained. I pulled my Hydroflame a few years back and did similar—turned out well, only I wish I had gone ahead and replaced the blower motor entirely (lubed the bearings which helped but didn't entirely solve the rattle/screech).

a photo would be step 1