Just bought a '78 300cd w/ 145,000 mls. In good one owner condition except that "accelerate" on cruise works but cruise won't lock in. Also sunroof needs to be "bumped" w/ the switch to open and close (sticks). Also rear windows only go halfway down unless helped. Bought both the Chilton's and Haynes books but no help on these matters. Any suggestions? Thanks, Marvin