I recently had to refit the fixing screws & nuts securing a multi-pole connector into a tightly packed electrical unit (all low voltage).
The heads of the screws were on the exterior of the unit enclosure. I was able to get the externally-serrated spring washers on to the screws using a pair of tweezers. However, the nuts (actually half-nuts) wouldn't stay in the tweezers or in the jaws of my narrow nosed pliers. (If Carlsberg made narrow nosed pliers they'd have a parallel action!) In any case, there wasn't room for the pliers.
My successful method was to cut down the flat wooden stick from an iced lolly to a suitable width and then to attach each nut in turn to the end of the stick with double-sided tape. Once the spring washer was in position I offered the nut to the end of the screw and turned the screw to engage the thread. Having removed the lolly stick, a little finger pressure held the nut while I turned the screw some more. Then the washer held the nut well enough for the final tightening.
This method worked because I was able to turn the screw from outside the enclosure. However, I'm sure it could be adapted for use where the male part is a fixed stud.
Best regards,
Swarf, Mostly!
Edited By Swarf, Mostly! on 13/06/2018 15:13:50