Which component is causing this?

[Jone5y]

When I alter the altitude of my scope through it's entire range of movement the returning beam from the laser collimator "drifts" across the centre alignment hole from 1 side to the other. It doesn't move much but is certainly easily seen and repeatable.
What would cause this?
I think I've ruled out primary mirror movement within its cell which leaves movement in the secondary holder (seems quite rigid), or sag in the whole top end due to a lack of support from the trusses. I am really hoping it's not this.

Can anyone think of any other causes or solutions to this prob?

Cheers
Steve

[Dennis]

Is the laser collimator “rocking” in the eyepiece holder by pivoting on a single grub screw?

Cheers

Dennis

[Jone5y]

Thanks for that idea Dennis. I just ventured outside to check if this was the case and unfortunately I can't get a beam of any kind just a flash of red when I try to turn it on. However, the collimator is held in place by a brass compression ring and couldn't be moved side to side by hand.
I guess that rules it out as the culprit then.