how does a DPDC work and possible repair methods...

here is the culprit
make an incision here, desolder the pins (so that they dangle in the holes, you need to remove the solder)
carefully open the cover
take out this rubber band carefully, it is attached to the ceramic board with resistive tracks
everything inside is perfect! See how the contact pads on the board have moved away from the pins - this is my mistake, I didn't desolder them right away. Good that the board didn't break. But there may be wear of the resistive layer on the ceramic part, in which case, as a temporary solution, you can apply this layer with a regular graphite pencil...
everything works but there might be wear on the sliders, then (again temporarily) you can bend them to make contact with the resistive layer of the board.
mistake. will have to solder the pins to the board now
soldered
check the holes for the pins before reassembly using a toothpick...
reassemble in reverse order. Press and seal tightly (preferably with epoxy)
seal the pins with solder
and again cover with epoxy.