When you have the belt that tight (all the way as you said). It will put too much load on the puley and make the belt fall off in the front. (my first had experience). I would suggest you set it to factory specs like it shows in the book. Maybe have it one notch tighter.

Check:
1) When you have the front belt cover off and turn the wheels at the same time... Does the belt seem to rest in the middle of the puley or lean to the outside?
2) Belt cover straight? If not try to figure out why.
3) Front tension Pulley installed backwards? (I did this by error and had your same issue)