Ensure that you check that the secondary is not rotated. A laser will not show this fault! You will need a Cheshire or sight tube.
Rotate your laser in the focuser. Does the laser dot waltz around the centre collimation dot? Then your focuser is not squared on to the optical and mechanical path. EVERYONE FORGETS THIS IMPORTANT POINT!!
Remember the order of collimation: FSP (Focuser/Secondary Mirror/Primary Mirror)
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