K,
Just went through this with my own that started leaking. Turns out that the plastic drain pan was just disintegrating after 10 years

It went down hill from there, I tried JB weld, then some of that two pc epoxy putty but ended up taking the ductwork apart and replacing the pan. Found out that the evaporator was corroded in one spot that didnt look too good, so new evaporator too ($400) The new drain pan was substantially thicker than the old one so it will probably outlast the furnace.
Mine started leaking when it was still warm outside so it wasnt too big of a deal. I did it with the help of a friend who does HVAC work. Actually I was his helper

Took us a couple of evenings. If you could see how my furnace is crammed into a closet you would not want to mess with it
Anyway, bottom line is that you probably wont be able to fix the pan. Just figure on buying a new one and I hope yours is easier to get to than mine is.