The caps will eventually fail, so it might be worth replacing them. However I don't know why that would take weeks, it usually takes an hour or two, and right back on the air. Does take some good soldering skills and a few tools. Despite that the FL-2100 wasn't a great design, there are lots of them on the air. They should have included grid current metering (the easiest way to "tune up" a tube amplifier) and used some better parts, but still they sold thousands of them. Sounds like you got a good one that wasn't abused, and that helps a lot. If you decide to sell it, I'd replace it with a newer design, like an Ameritron AL-80B. Small footprint, not terribly heavy, but a very robust amplifier that rarely fails.