I have a '96 ('95 built) Cherokee Sports 4.0L petrol AT w/ AC. Recently the idler pulley (Flat) jammed and the belt snapped. What belt size is the correct one, 2275 or 2500? Also, apart from idler pulley, is there any other pulley that normally fails that I should change as a preventive measure? What about the second idler pulley (Ribbed) under the flat idler pulley.

Also, what is the best way apart from the thumb to check the belt tension?

Last, how often should the belt be changed on these engines?

Any DIY guides with pictures would be helpful, otherwise I might write one up when I do it.

What is the OEM brand of the pulleys and the belt?