The procedure to replace the airmix actuator in an (1991-1996) Olds 98 and some 88* are as follows
1: empty the glovebove
2: Remove glovebox by removing the 4 screws securing glovebox to the dash frame at the bottom of the glovebox. They are either 5.5mm or Phillips head screws.
3: Remove the module above the airmix actuator by removing the one 6mm screw, slide it towards you and position out of the way to the right. Theres no need to disconnect the wires.
(This will give you enough room to get a small 1/4" ratchet onto the Airmix Actuator screws without much problems.)
4: pop the airlix lever off at the threaded end of the rod.
5: remove the two 5.5mm screws. The second one is on the far side of the actuator almost directly across from the one you can see. Feel along the rear side until you find the circular recessed area; the screw will be in there.
6: Disconnect the electrical connector.
Installation is the opposite of removal. Be sure to calibrate before connecting the threaded rod.
This is a very simple part to change out. I pulled and disassembled 3 at the yard in under an half hour before I found one with a good gear.
New part#'* - ECC - 16141822
................ non-ECC - 16124942
* I got my junkyard part from a 1998 Olds 88 and it was setup exactly the same as our 96' 98. I do not know which years of the 88 would be the same.
Maybe this will help someone sometime.