Drain plug on pump is stripped out.

Repair for this depends on which part is stripped out. If the threads on the brass plug are stripped, then it may be as simple as ordering part number 6134 (new drain plug and nylon washer). If the threads in the aluminum block are stripped, then the block will likely need to be replaced. If the drain plug head breaks off due to overtightening and the pieces cannot be removed from the hole, then the aluminum pump block will need to be replaced.