Maybe I missed something here, but just in case, did you remove the bobbin base from the machine yet? I mean, I guess that would be obvious to me, but just in case. I sort of reckon you did, in order to do a TF soak. But if I had it out, I would soak in some PB Blast sprayed into a small container. The other thing, I don't remember cause it's been awhile, but is that the only screw holding that gib on? I can't see how much of the screw head is missing, but I'm thinking you could almost take it off with what's left of the screw head still there. Then you'd have more to work with and easier to boot. I probably just missed something. And we're looking at one of these, correct...
http://www.ebay.com/itm/400675332284...84.m1423.l2649