Well, bad news!
Took it to the co-op today to start the process and found that the seat tube has a spot in the middle that is not round and appears to be "crushed". The mechanics recommended that I not ride it as is
Don't give up just yet! Show us the damage as clearly as you can. It sounds, to me, like a problem that might not be that hard to rectify. Anyway, let's see the damage more closely, if you don't mind.
As for the mechanic, is he knowledgeable about vintage bikes? In the area in which I live, there is only one shop that still has an old timer working there. And even he does not know it all, even though, at one time, I thought him to be a vintage bicycle guru.