Re: Problem with chain.
One thing that helps with the tensioner is to put a bit of twist in the mount to align the roller with the chain. Normally the chainstay isn't parallel with the chain which puts the tensioner roller at an angle to the chain. I think the tensioner assembly that uses two straps and four bolts to clamp on the bike instead of the one that uses only two bolts and one strap is less likely to move. The two straps allow the clamps to accomodate themselves better to the shape of the chainstay.
Goldwing 1500, Silverwing 600, Schwinn 49