I designed the FLI to Tak unit so there was just a few mm of travel required to get focus. With the draw-tube virtually all the way in, it feels very stable.
Indeed, CCDinspector results confirmed there is now very little sag or random tilt.
I just need to do some measurements and the math to work out where to place the shim spacer(s). ....clear weather would help
I'll post the results when I'm done