The deal is with this mount at this price point the mechanics are not perfect. So you will find that the mesh tightness is not uniform around all 360 degrees. This means that when u set the tension you need to rotate the thing manually all the way around.
But great catch. I am sure this is something that needs adjustment (your new shims) or at least looked at for people who want to tune things up.
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired