I picked up a RV-4 Deluxe a couple of weeks ago. The scope is in very good shape and looks like it was hardly used. So a few nights ago I started the restoration process. I plugged the drive in and the scope didn't move. Off with the cover for the clock drive to see what is going on. The first thing I noticed was the drive had never worked since there was the original glob of grease on the worm and rest of gearing was free of grease. That told me the motor had never rotated the worm. I took the worm assembly off the scope and plugged the motor back in. Still no movement so I took the motor off the worm assembly. The shaft on the motor spun freely, not good. The motor is a fairly common 1/10 rpm pear shape unit but the output shaft is special in that has a slotted end. That part could be made fairly easily but I decide to dig into the motor to see what was wrong and if it could be easily fixed. So out comes the antique high wattage soldering iron to try to unsolder the motor case and get into the gear box. It took awhile of heating the solder and scraping it away but after about 30 minutes I had the case open. It only took another minute to find the problem. The gear that drives the output shaft had come loose. It is a press fit on the shaft and the knurling on the shaft was too short to really grab the gear. So I carefully pressed the gear back onto the shaft so it was square to the axis of rotation. The mechanical bond was too weak to firmly hold the gear in place so I used one drop of super glue at the joint and let it cure over night. The next morning it was firmly in place but for safe measures I added a little of JB Weld epoxy around the joint and let that cure while I was at work. When I got home last night the gear was very firmly attached.
I reassembled the motor and plugged it in. The output shaft turned smoothly and timed the rotation to be sure nothing was slipping. All looked good so I soldered the case shut in two places
The next step was to mount the motor and adjust all the parts of the drive. The first was the worm assembly. It didn't turn perfect smoothly. I took it apart and lightly sanded the end of the brass take up assembly. That fix the slight hang up I was feeling. I then carefully tighten the brass take up screw on the end of the worm shaft until there was no slide to slide movement of the worm in it's housing but it still rotated freely and easily. Then I tighten down the locking nut. Next step was to reattach the motor. I found the holes in the motor brackets and those on the worm assembly were a little off and could cause the motor to bind. A small file was used to enlarge the holes on the motor and now the motor dropped into place.
I then powered up the motor and put a piece of tape sticking off the worm so I could see the motion of the worm. It ran smoothly. Next I loosen the clutch on the main drive gear. Now the scope was free to move in RA and positioned the counter weight on the RA shaft so the scope was balanced. This results in the least amount the torque needed to have the scope track and the least amount of wear on the motor. Next I reinstalled the worm/motor assembly back into the clock drive housing and adjusted the worm so it squarely meet up with the main drive gear. I tighten the clutch and rocked the scope back and forth in RA to see how much play there was between the main gear and the worm. I adjusted the worm assembly to just remove any play making sure it wasn't too tight so the worm wasn't jammed against the main gear.
Took the scope out and looked at Jupiter. Scope was tracking, most likely for the first time ever. The next step in the restoration is to straighten out the problem with the diagonal mirror/focuser issues since the diagonal is out of alignment but glued to the metal stalk that is part off the focuser.
Here are a couple of pictures showing the motor being repaired.