when collimating with the OCAL, is the scope on the mount? if so what direction is the scope pointing, and does the collimation (according to OCAL) change as the mount slews? that might help isolate where the problem lies. And given the trivial weight of the OCAL, if collimation remains solid according to OCAL no matter where the scope is pointing, that would suggest the issue is focuser related (maybe drawtube sag from the weight of your imaging camera gear)
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