Cooling fan belt 753 L

[smokey196240]

I keep loosing the cooling fan belt replaced the belt works good at low RPMs but if RPMS go up the belt gets thrown off any one have this problem

 

[foton]

I would think it could only be few things either there is a pulley alighnment problem or the auto tensioner(if you have one) is not putting the correct amount of tension on the belt of course it could be a combination of the two. Check all bearings for slop.