Thanks oxymoron - I do actually have the w116 chassis HVAC manual, and I just did a quick and dirty look to see if the rheostat was at fault. I discounted the servo because the thought the aluminum bodied ones were a final solution. It appears I may be mistaken. I will follow the procedure more closely and verify before I drop $500-700 in a new servo or the unwired replacement kit.

Besides the aluminum servo, my 6.9 has recently had its radiator rodded out, and new hoses all around to cure an overheating problem. I guess the crud that got the radiator also may have gotten the servo.

Does anyone besides Performance Products carry with unwired kit?