Looking for an old Dia Compe part

Anybody got any suggestions as to where I can get replacements for the
plastic quick-release cams for mid-'80s (I think) Dia Compe road
calipers? These are the ones that work with a metal wingnut-like
thing to allow the caliper to be opened for wheel removal. Two local
shops professed not to know where to get them, but that didn't
surprise me much; they were not my favorite sources. I've got one
that's broken out completely now, and another that's cracked, and I
don't relish the task of whittling out new ones with the Dremel and
the drill press, though I have figured out a way that I can do so if
necessary. (I'd probably swap my spare 105 calipers on to the bike
before I'd make new cams, though.)
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