The three plugs will only fit in the correct socket - they're all three different. from memory, one has five, one four and one three.
The only way to do it is with a pair of good tweezers that you can use with a good light source to guide you. It's hard to determine when you'e got it in the right position, but look carefully at the pins and how it goes together. It takes a little bit of force to get the plugs seated, but once you're sure it's right push with the tweezers on the top of plug, not on the wires. A broken wire puts you out of business .
I had to remove the gimbal a while ago, and at some point later I started seeing faint diagonal lines in the FPV. Sort of like the old TV pictures with interference is the best I can describe it. It drove me crazy and I checked everything trying to track it down. I finally went back and carefully separated each ribbon cable from the other, so that one goes up on one side, one in the middle, etc. Flew, and bingo - interference gone, and a clearer FPV image too.