broken focus knob on Meade ETX-80AT

[DBizzle]

Newbie here, just getting started but all the great info here on SGL has got me pumped!  Thanks to all the great contributors! 

Got a Meade ETX-80AT-BB recently from a neighbor, new in the box, but no warranty.  I followed all the instructions and got it set up, and took my first looks at the moon - just long enough to get that "oh WOW!" feeling - when all of a sudden the focus know quit working.  I could turn it either way at end, but nothing affected the focus... apparently the focus knob had become "disconnected".   

I started looking at it a little closer, wondering if it was something I could fix myself, and I noticed the objective lens cell was loose - in fact I could lift it completely out of the optical tube!  I noticed, too, there was something rattling loose in the optical tube and when I turned it upside down a tiny nut, washer, and slightly larger gear piece fell out!

I'll post pics of all the parts I'm working with, if anybody has any help or advice on how to get this put back together I would be greatly appreciative!   I'm pretty handy with tools and whatnot, and pretty good at putting things I take apart back together, but since I didn't take it apart (or been able to find a schematic of the internals) I'm a little hesitant to dive in.   (I don't think I'm missing any parts, but I can't be totally certain.)

The objective lens cell: note the "focus rod" is threaded at the bottom to go further in or out of the tube body, and the top tier of the rod is also threaded (probably to interact with a gear in some way?)

Optical tube, eyepieces, and base: note the focus knob can be lifted up a bit (but not completely out), with a screw hole at the bottom.  There's a Phillips screw on the base below the focus knob to provide some sort of internal access.

 

 

 

 

 

 

 

 

 

 

 

 

Rear view of eyepiece base, with additional hex screws (the 3 farthest away and out of focus, sorry):

View down the inside of the optical tube:

And finally, the 3 loose parts retrieved from the optical tube (US Penny for scale):

 

 

I'm not opposed to taking some of those screws out and having a peak inside, but I wanted to reach out and do as much research as possible before I started.  ('Cause, what's the worst that could go wrong, right? )

Thanks in advance, cheers!

[saac]

The focus mechanism on the ETX 80 AT is the weakest part of what is otherwise a decent little goto scope.  I've often thought about taking mine apart to make some improvement but never got any further.  You may have some luck searching out Weasner's Mighty ETX site; mainly concentrates on the ETX125 but there is a wealth of information on Mike's site, you can email him questions directly.  I'll be interested to see how you get on.

 

Jim

 

http://www.weasner.com/etx/menu.html