The reconditioning of the pump latch for my Monotype caster is now complete. I found some donors for the missing screws in my parts stock. There were two of the actual latch trigger assemblies there (but not the rest of the latch) so I took two screws from one of these.
I used the Loctite Form-A-Thread kit to improve the fit of these screws in the holes I had tapped for them. The tap I had used was a standard modern #8-36 which makes the threads slightly larger in diameter that these screws, and perhaps the vee angle of the threads is different as well. The Form-A-Thread kit consists of a 2-part epoxy filler material and a coating to apply to the screws to prevent the filler from sticking to them. You coat the screws, measure out equal amounts of the two components of the epoxy, mix well, put it in the holes, and screw the screws into place. After 5 to 10 minutes you remove the screws again and give the filler half an hour to finish curing. This stuff is usually used on larger holes and I found I had a bit of trouble getting any down into these relatively small holes, but I seem to have put in enough that the screws now thread in without any slop. I was thrown a bit by their statement that the filler starts to gel in about 5 minutes, but I was finding that the remnants on my mixing board seemed to remain liquid. Perhaps exposure to the air slows or inhibits hardening.
In any case, everything is painted and assembled now, and a few drops of oil makes everything operate smoothly:
The long spring along the back should probably be replaced. It already had an end broken, and when I tried re-shaping the last turn of the spring to make a proper hook again, part of the wire snapped off so perhaps the entire spring is suffering somewhat from metal fatigue. Fortunately, I already have some #24 steel music wire to make a replacement when the time comes, and I have also already measured this spring so I have all I need to replace it. Someday…
So the only task left is to make the longer spring rod. Oh yes, there is also the extended-stroke piston rod to complete.
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