[Tandum (Robin)]

I'm trying to setup a new newt but the laser is showing movement and maybe someone has some ideas on what to look at next.

What is happening is I have the newt on the mount, counterweights down, newt pointing west and center the dot on the primary. If I rotate the newt east, the dot moves to the inner edge of the primary dohnut. The focuser is now reinforced with Galv Plate, see pic, and I can hang alll the camera gear off it, in a bag with string, 2.6Kgs worth, and the dot remains dead centered.

I have unscrewed the 3 collmination screws right out and screwed the secondary center bolt tight to fully tension the spring, recentered but with the same result. I've added washers to the spider to get it as tight as I can, same issue. I've moved the tube so the rings where close to the focuser in case the tube was deforming somehow, same issue, but the bag of camera bits would have shown this as a problem I guess.

All I can think of is to remove the primary and stick paper there to see if the dot moves with the primary out of the picture. Apart from that I'm out of ideas. Also note the focuser may not be square to the scope but I doubt that matters in this instance.

I thought I'd fixed this with the galv plate, but apparently not. Does anyone else have any ideas on what to look at?