dmorgan, when adjusting that style tensioner you must loosen (a turn or two) the allen head bolt in the center of the tensioner, otherwise you destroy the tensioner rod threads ... as you experienced. Recommend buying an entire new tensioner assembly since they fail as they get older. Get a new tensioner shock absorber also. As Lee mentions removal/replacement is quite involved and tedious. Best to clean the area thoroughly so you can see all the bolt heads and positioning of components. Take particular note of the orientation of the tensioner parts because if you install them incorrectly the tensioner will not function properly. Allow plenty of time for the removal/replacement and have patience.

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Fred Hoelzle