I likely have a different generation of A3 combo unit that you, but did experience a similar problem with the locking handle on mine. My solution was to simply not leave the locking handle tightened all the way. My practice is to tighten the handle all the way then back it off slightly and that brings the beds into complete alignment. The setup guide for my generation of combo machine is here:?
A word of warning on those Preston videos from YouTube: I found them to be very facile and primarily useful in scenarios where everything was aligned/calibrated 99% of the way already. For anything major, following the advice he dispenses is insufficient and likely to leave you confused more than anything.?
