[Glenhuon (Bill)]

If you want to rotate the secondary a bit, slacken off the centre screw a very small amount, just enough to let you turn the secondary holder, but not so its loose. Best not to touch the other 3 until you have it centred. A cheshire is best for it but you can substitute a black camera film case with a pin hole in the centre of the base as a peep hole. Adjust it by small amounts until the secondary mirror looks round looking through the peep hole and gently tighten the centre screw.
If you find the secondary is too far up or down the tube slacken the centre screw by 1/4 turn (Max), adjust the other 3 equally in to go down tube or out to come up tube, gently tighten the centre screw and check through the peep hole.
Put the laser colimator back in and adjust the other 3 screws by tiny amounts in or out to swing the lazer beam on to the centre spot on the primary mirror. You'l find the adjustments are very small for quite a large movement of the beam on the primary.
When that is done you can begin adjusting the Primary colimating screws to get the return beam into the correct spot in the colimator.
Its a bit fiddly, but once you have done it a couple of times it doesn't seem so bad and secondary adjustment is usually just a small tweak after it is set up initially.

When that is done you can begin adjusting the Primary colimating screws to get the return beam into the correct spot in the colimator.

You might find the beam has moved off the centre spot a fraction after primary adjustment, tweak it back on and adjust the primary again to get the return beam back on target.

Thats my method and it seems to work pretty well.
I've found that it seldom moves on my 150 newt and the only adjustments required now are an occasional tweak of the primary.

Cheers
Bill