Hello I iwll help you with your question,
If you haven't replaced the tensioner yet it is the problem. The tensioner can bind inside so it is using all its force moving the piviot in the tensioner and not putting enough force on the belt.
Clean all belt dressing or oil off all the pulleys and install a new tensioner and double check the belt number for the correct application.
Let me know what I can do to help you with this
Did you replace the tensioner assembly or the tensioner pulley?
There is only one position for the tensioner but it is possible to pull too hard on the tensioner when installing/removing the belt and this will crack the case leaving insufficient tension on the belt. A squeeling belt is a sign that the belt is too loose and is slipping or misaligned.
I don't know what brand of belt you are using but the Gates number is K060882 and your bbelt should have some variation of the 6 rib 882 length in the number.
Let me know about the tensioner
The belt routing is shown below so be sure it is routed correctly