I think youre right about the brackets.
I was studying my haynes manual last night and it says some engines have the tensioner above the idle wheel some below and some dont have it at all!

I think I'll just get a belt to start off with and see what happens, I will try to ask a dealer for an apinion also (not that I think they will know any more than the people on this forum).

I've heard the tensioners break and it looks like the one I have is an aftermarket one. Seems like changing the belt is a risky business!