I have a 2032 that I noted the Power and Dummy unit occationally disconnected last Christmas. I procrastinated for a bit, but now I’m cleaning my layouts for the comming Christmas. I see the rear coupler head has apparently got a lot of up and down free play on the rear power truck. I was looking in my k-line repair manual pg 177 and it shows the rear coupler is attached to the drawbar assembly with a drive screw. (202-9) I see no slot to use a screw driver to it screw down with. Is this to be done by hand? If so, should I apply loctight to keep it from loosening up again?
Drive screws are pressed into a hole, which is a lot faster in production than scewing a bolt in. They are meant for making a permanent joint, thus no slot for a screwdriver. The threads are also different than found on a bolt.
The drive screw may need to be tapped in with a punch. If the hole is too big now and the drive screw is loose, then you may need to apply a permanent adhesive to keep it in place, or possibly put a few strands of thin copper wire in the hole to shrink it before you drive the screw in to allow the threads to bite into something.
I checked the rear couplers on my 2023 set. Like yours, the zinc coupler body is not tightly connected to the drawbar. However, I was unable to drive the screw any farther into the casting nor pull it out. It goes into a blind hole which I imagine is not deep enough for the length of the drive screw.
Your drive screw may not be as far into the hole as it will go; or it may be like mine and is as tight as the original design will allow. If you want it tighter, you may have to drill the hole deeper. If I had to do it, I would drill into the casting from the bottom, drive the old screw out, then tap the hole for a machine screw or drill a clearance hole and put a nut on the bottom.
My set is a pair of powered units, permanently coupled because of all the wires that connect them electrically. You might just make your coupling permanent with a Ty-wrap to cure your uncoupling proplem.