My question regards a 91 cougar, V6. I am attempting to replace the serpentine belt and the problem has been in finding a way to adjust or unload/reload the tension on the belt. I've placed a photo of my tensioner at the end of this message. It appears that the pivot point on the left which is where the tension is actually adjusted but I haven't been able to find any tool that fits in there. There seems to be a countersunk multi-point nut or screw of some type but I can't figure out how to adjust it. It seems to require something similar to a ratchet drive or large allen wrench but I can't find one which will fit in there.

I went out and got a "Universal Serpentine Belt" tool which supposedly will let you adjust any tensioner available. It has "3/8" and "1/2" ratchet ends plus a selection of socket and open end wrench ends. *Nothing* on that supposedly "Universal" belt tool (including the ratchet drive ends) would fit my tensioner however and I am completely stumped at this point.

I've also been told that the nut on the right hand pulley is actually the point where you adjust the tension. That appears to me to only rotate in the same direction as the pulley (to let you change the pulley) however, and doesn't seem to me to have anything to do with changing the belt tension. I am completely flummoxed by this at this point and hopefully someone out there who knows this vehicle can help me figure out the mystery of this tensioner. Thanks in advance.