It sounds like your just-rebuilt starter might need a rehab. Does it have a solenoid, or is it the old stomp-start model? There are two windings in the solenoid, a "pull-in" winding to get the gear engaged, and a "hold-in" winding to keep it engaged once the starter is turning. The pull-in winding grounds itself through the starter brushes, and if the brush circuit gets interrupted, there will only be a click from the hold-in winding because it lacks the strength to complete the starting process. You've either got a bad solenoid winding, a bad brush set, and/or a poor ground. Check all your connections, hot and ground, and make sure the pull-in, and hold-in windings are in good condition.
Jerry
