I stumbled onto this post just browsing this forum.

I will try to describe an issue that I had when I bought my LX90 about 5 yrs ago.

The scope was making some vibratory noise from the right arm. It also was not moving smoothly (Dec) when I would slew it at slower speeds.

Long story short, The large ring gear was rubbing, but just barely, against the right fork arms INNER plastic cover.

I had to literally cut/sand a portion of the plastic cover to keep it from rubbing on the large Dec gear.

It was difficult to diagnose, and after enlarging the inner plastic cover that was rubbing the gear, it worked perfectly.

Thats the short version of an issue I had.

Wanted to put it out there, in case it could be helpful.

Ken