I'm not there with the arthritis...yet, but getting that last round in sure can mar the case up to something ugly with new or NOS enbloc's, even after tumbling them to smooth out the park, and flexing in vise to make them more springy.
Santa sent the kiddos a 3D printer for Christmas. It's in the shop being put through its paces on all kinds of odd bits while I figure out what temperatures it likes, etc. The kids are right there in the shop learning freeCAD. Thanks baker, I'll be printing that handheld one now.
EDIT: Are you able to share the .stl files here?