1. How much play is tolerable at the input gear of a Century C head? When I turn the machine by hand, there is about one-tooth width of play where I can rock the drive gear back and forth without moving the rest of the gear train. Seems awfully sloppy to me. How much is too much?

2. For cleaning, I wanted to remove the sprockets on our SH-1000. Removed the screws and used a touch of solvent to loosen up the sprockets on their shafts--they spun freely on the shafts, but I couldn't get them to slip off the shafts. The parts drawings I have aren't clear as to how these things should come off. Am I missing something here?

3. The oil-level viewing ports on both of our Century intermittants are so dark that we can't see the oil. How much of a project am I creating by removing the operating-side cover in order to clean those little ports? Or is this something that should be left to an overhauler to do?

BTW both heads appear to be lubed adequately and all of the bearing cups have been oiled. Both heads run smooth and quiet, but not being able to see the intermittant oil level is bothering us.

1. Seems like that is an awful amout of backlash in that Century. I would guess that gear on the mainshaft is badly worn. Unless someone knows a trick I don't know, you are not going to be able to adjust the backlash without screwing up the mesh of the gears that drive the projector holdback or feed sprockets. I would look very closely at the gear for wear.
2. Removal of the sound head sprockets should be easy. They should pull right off the shafts. Make sure the set screw is backed out far enough (sounds like you have) and make sure the film stripper is not fouling the sprocket.
3. As far as removing the cover from the intermittant movement, it is best to remove the movement from the projector before you try that. Have a new gasket handy, but beware - you might have to re-adjust the dwell and cam shaft end play after you do that.

I don't know of a flushing oil that will clean up the oil level sight glasses. Perhaps some of the other gents might be able to give direction on that issue.

On Centuries, I have found that the screw loses it's "grip" on the flat spot and starts to allow the gear to rotate on the shaft.