Re: Battery Fitting - Pesky Strap...
David C has suggested what i was going to.... check all dimensions of the new battery to that of the old one. If fatter or taller it will take up the *slack* in the strap.
This strap anchors at both ends, maybe it is too far down or caught in the battery tray somewhere.
If the new battery is the same size as the old then the strap should still work. You just need to re-trace thro your step to find out where it went wrong,.... maybe the strap is twisted?
ALSO: make sure that the battery is *fully* seated down into the battery tray & its plastic *cup*. if its base is wider then it will not fit down correctly, making the battery *taller* than the old one.