Meade LXD55 SN10 secondary problem

[StarBru]

I recently bought ANOTHER Meade SN10. Why, you may ask? To make a long story short, it came with a JMI case and an upgraded JMI NGF-55 motorized focuser which I wanted for some time now for my other SN10 and have not been able to procure. On inspection of the secondary, I noticed the central screw that holds the secondary was loose and I tightened it. In so doing, I then noticed the whole secondary assembly where it attaches to the corrector is loose and rotates. It will not tighten enough to not move. My other stock SN10 does not have this problem.

The previous owner had to take the corrector off of the tube to upgrade the focuser, and the OTA still has the tape and arrows lined up as that procedure requires, but he must have also loosened the central screw at some time to collimate it which is not necessary and you are warned not to do for fear of the secondary crashing into the primary mirror. I intend to remove the corrector and primary to give it a good careful cleaning anyway as both are extremely dusty and have a few foreign objects that need removed as well for it to be all it can be. I then will attempt to resolve the problem.

My question is, has anyone else had experience with this problem for a Schmidt Newtonian or similar scope, and what had to be done to fix it? Hopefully the assembly is not stripped and I just bought myself a parts telescope for $400!

[Don Quixote]

I am not sure this applies, but.

On one of my SCT the secondary was loose. It rotated. I do not know if the orientation of the secondary is as critical is the orientation if the corrector plate.
That being said, I found that the secondary is held to the Corector by the threaded collar that surrounds the secondary on the inside of the corrector plate. This collar is a short portion of cone and seems to act as a baffle for the secondary in the SCT. I further discovered that in a prior life someone had not tightened this collar all the way. I further discovered that the thread on this collar are very fine and must be gently threaded and slowly tighted or the thread will jamb and give the feel of being tightened securely when in fact it is not quite so. On some corrector plates this cone is plastic. On some early scopes it is metal.
In tightening the plastic one it is easy to over grip and distort the threaded end which I found on the SCT I was working on.

I solved the problem by removing the collar carefully and reinstalling it, threading it on gently.

[StarBru]

Thanks, Don Quixote. That is some good information and should apply if that is the case!