Just put a "rebuilt" D-type in a 63 B. As long as I don't drive longer than 15 minutes, the OD engages perfectly, but 15 minutes ain't far in Atlanta. After 15 minutes of running, the solenoid engages but the OD hunts between engaging and not. With no throttle, the RPMs come down but with throttle, they go back up (as if the clutch is slipping). I've been told to remove a "spring, ball and hollow pin) from the top of the unit and clean out a hole on the side of the tube. Is this feasibly the problem. Need to be relatively sure since I have to pull the power plant. Help, I want my OD back.