Re: Got problems, please help!!
The hole looks to me like it won't affect anything but looks. I wouldn't bother trying to patch it myself.
As far as your loosening problem, I'd try two nuts like thunderhead suggests. I do this on all my engine mounting studs whenever there is ANY sign of loosening. Works great and is much easier to remove than loctited hardware.
As far as your tensioner problem, I tack weld mine to keep it from rotating into the spokes. Any muffler shop with a MIG can do this in seconds, usually free if you let them check out your cool bike!
If more is better, then too much is just enough.
If you can't afford it, build it yourself.