Remove the audio preamp just far enough to gain access to the other PTO mounting screw, and remove it. Then, after removing the drive gear from the PTO shaft, and disconnecting the three wires going to the feedthrus on the side of the PTO, the PTO is free, and ready for rebuilding. This is wehere the real work begins. Ten-Tec cautions you to note its orientation so you can replace it the same way. Once you have the key out, the tuning shaft can be pulled out, at which time the 3 ball bearings are exposed.
Chances are they are pretty grungy, but they'll be replaced later.
You can clean the loose metal parts with whatever detergent or degreaser or solvent you have on hand. And don't get anything except alcohol anywhere near the electronics. Pay attention to crevices. This is the longest part of the job, because this gunky, dried-up grease sticks to the parts like epoxy. Reassembly After cleaning, wash your hands and clean up the area.