I too had the same difficulty with my Craftsman 16 inch scroll saw which I have owned for about 10 years. I disassembled it, figured out what the problem was and ordered parts to fix/replace the lower arm and repair the broken air bellows.
I ordered parts online at the Sears repair parts site to repair it. I figured that I would rebuild the saw since I had it all apart. I like doing this sort of thing.
After about a couple of weeks, about $100 worth of parts, and some assemble, disassembly hassles, the saw now runs pretty well. I'd say it is adequate for my uses. Granted I have never used the Dewalt, Porter Cable nor other saws so I really have nothing with which to compare.
I don't scroll so much any more since my wife "mandated" that there is no room for "all that stuff" in the house any more. I'll keep the repaired Craftsman Scroll Saw since I like it and don't feel like spending another $800-1000 on a new "super saw"
That being said, if you really want a new and better saw "in the near future", don't bother fixing the Craftsman saw and go with the other folks say. I would too if I had the extra money to spend.
Walt in CT