Got mine from Old car parts NW in Renton, WA. Not that expensive and would guess that would cost more to rebuild. The gent`s name is: Ray Orme, ph (206) 300-1083 or
[email protected]. It was a NOS in the original packaging and cost less than what people were asking for used units. Works great. The 4 pieces you are wondering about help control what takes place internally when each button is pushed. The plastic back is originally held on with plastic nibs which are now broken and if you were lucky enough to get it back together and working would have to be glued back on. You will be further ahead and happy with this original mopar part. Good luck!