Posted 14 February 2013 - 05:29 AM
Since I had some experience in disassembling a Mewlon (mine), I can give you some hints.
I suspect the problem is one or both of the following:
-- the primary cell has been stuck on the baffle tube.
-- the focuser knob's moving mechanism stuck for whatever reason.
As you can see, all of this is can be resolved to perhaps one thing: the grease used within them.
The "only" problem is to determine what went wrong you have to remove the whole primary cell. This can be tricky, but it is pretty straightforward. Here are some key points:
-- always mark the original positions.
-- remove the primary mirror.
-- there are screws under the screws in the cell. This also means...
-- ...don't force anything. If something doesn't move, look for an another screw. Takahashi was nice enough to hide some in the cell.
-- if you have removed the primary mirror, removed all screws and everything, and the cell still doesn't come out (or at least, goes out hardly), then we found problem #1.
-- if the cell goes out easily, then the problem is with the focuser.
When you put back everything an extremely great care must be taken, otherwise you get a mirror shift. I know since I have about 60" from the none. Count the rotations while screwing back. I also advise to do this with an ATM friend. He might have more tools and ideas in solving this problem.
I hope this helps somewhat.