[knotty panda]

I use vermeil. No problem. I don't use Champion but from what I recall, D or E is similar to my buttonhole twist. If your clasp has a normal jump ring on the end, 26 or 24 ga., 1/4" of gimp should be plenty. The medium, heavy, gimp description, I think, refers to the size of coil. You shouldn't need heavy. The only other thing I can think of is, are you using a flush cutter on the gimp? If there's a bit of a barb on the end, sometimes that might cause it to disintegrate. Is the gimp that's failing you from Fire Mountain or is it that Beadsmith crap? Work gingerly with it. Don't try to force it to slide down the thread. Lift it from the box like it's a butterfly and put it back in just as delicately. When I cut it, I sort of eyeball the length because the way it wants to lie on my bead board ruler, is the way I keep it. I guess I coax it into position rather forcing it. Sorry I can't be of more help. Sounds like you're doing all the right things.