How do you loosen the idler pulleys on a 1995 Mitsubishi Montero LS?

In the center of the drum/pully there is a bolt (or nut, depending). This is what is locking the pully in place. Loosen it (no more than it takes to free it) befor turning the adjuster. Be sure to loosly snug it down to check your final adjustment and if correct, then you can tighten it all the way. (If it is too loose when the adjustment is set then the drum/pully will move when you tighten it and throw off the adjustment.)