Maybe a little more help for you
I was going to mention the same about the cable control connections, but here is somthing else that might help: I noticed that my plug has a rather large outer rubber jacket that is interfered with by the car cradle, a plug with thinner or maybe shave yours down so it does not rub the car cradle hole will help.
VX6600>VX6700>VX6800 DCD 3.0.0/3.55.04>
TP2 (stock, not inspired to mess with it)>
HTC Incredible, ROOTED BABY!
THUNDERBOLT, ROOTED ALSO!