If my EQ6 did that I would be thinking binding or general bad gear meshing. If the LX90 is anything like the LX200 it is really easy (and safe) to get into the mechanics on the fork arm for a general inspection. Might be worth a shot.
The LX90 is far from quiet. When slewing @9 you will definitely hear the gears meshing. Try slewing @3 it should be quiet, if it isn't you may have a problem. The gears on the LX90 are "agricultural" on a perfect unit, there will be quite a bit of noise at medium-high slew rates.
Yeah the slewing is noisy but at certain elevations it departs from what I would deem normal. That is to say it reaches a vibrational frequency that creates a higher pitch which has an unnerving resonance
I found mine was not only noisy, but also had poor backlash stroke pointing ability.
So I stripped the covers and had a look.
I found the original manufacturer had used quite a lot of loctite which had not all gone where it was intended.
So I removed the worm modules and cleaned all the screws and bearings then removed the strange biomass from the wheel that equates to grease in China or Mexico.
Replaced it with moly grease and replaced the worm modules . All of a sudden the meshing was reasonably accurate and backlash had all but gone. The noise much diminished.
The nice thing was the worm modules are sprung and now engaged with proper and repeatable accuracy.
Proved once again last night by unerring centring of targets all over the sky.
Witnessed by all at the SAS meeting.
