Celestron C80 ED problem

Hello all!, I really love this scope. its optically superb.
but it has developed a little problem. I have the c80 ED mounted
on a vixen porta mount and since I use the WO binoviewers sometimes,
I had the tension on the alt axis turned up to hold the scope steady.
I sometimes slew the scope by grabbing the scope instead of the slow-mo
(bad idea with the extra tension, I know ) not the focuser tube moves
inside the OT enough to shift the image while focusing. i.e. if I press
down unpon the EP there is a distinct movement.

I took the focuser apart and the tube out and I can see 2 white strips that
seem to be what holds the cylindrical tube inside the conical back end of the
OT. Perhaps these strips need to be replaced? Anyone seen this before
or know how the focuser tube is held straight inside the OTA? I know I should
get a different focuser. The helical one in the C80 ED sucks but I'd like to
work with this for a while before getting another focuser..

Thanks
Ashok Srinivasan

Ashok:

There are two small allen screws on either side of the focus lock screw that adjust the play of the drawtube in the focuser. They are quite small, I believe they require either a 1.5 or 2.0mm hex key to adjust.

The typical Orion/Celestron rack and pinion focuser is not the best but with some care it can be functional. I have reworked a few dozen of them, this is what I typically do:

Remove the rack and pinion by removing the four screws. I remove the draw tube and the pad that the lock and those two adjusters push on. I then clean the "grease/glue" from all the parts as best I can and relube them with light Silicone grease.

Assembly goes like this: First I put the lock pad in place and install the drawtube. I then adjust the two small hex screws so that the drawtube is moves in and out with a small amount of friction but does not move or rattle off-axis. Determining the ideal force on those screws is a matter of trial and error and it may need to be done while the scope is in use.

Next I install the pinion gear and then play with adjustment of the 4 screws that hold it in place. If I am using a 1.25 inch diagonal and the eyepieces are light, I will probably leave them somewhat loose as it makes for a better feel. But with a Binoviewer, you should probably just snug them up.

Jon