So this issue began with this grinding noise, which was correctly diagnosed as a failing servo by Southern_Runner (Thank you again). I ordered up the part, and was wondering how to attack the 4th screw problem that you'll see varying solutions to on the forum, and then we had a long hot summer here in the SJ Valley where the A/C began to blow warm on one side, the characteristic low refrigerant symptom. I had it serviced, and within 3 weeks, it was doing it again. I had them search all the engine bay components for leaks and none were found. This then pointed to an Evaporator Core leak which is not too uncommon at this age (16 yrs.). On recommendation, I had an A/C shop use a sniffer to confirm the Evap Core leak and it was present. I then ordered the remaining servos to have replaced in order to not have to replace them one by one as they failed. If you've researched this, the whole dash has to be dismantled in order to replace that core. I ordered up the parts and elected to have the shop do the labor. Anyway I'm happy to report the core has been replaced, along with all the servo's and the 4Runner is back in business, holding A/C system pressure, and no squeaks or messed up dash sounds. In the pic you can see the the old servos, and the area on the core where the leak was present.
Old Core and Servos