Laserscript user forum

Hello, I'm hoping you may be able to help me with my 8 year old co2 900/600 laser. We have just fitted a new bulb and can line up the first two mirrors fine but the 3rd mirror goes really out of line when moving the dolly from front to back. Have measured the distance from the back of the machine to the front of the bar that the dolly sits on and there is a 10mm difference at each side. When you measure at the front there is no difference.
Could this be the cause of the problem and any ideas on how to rectify?
Many thanks, Ian

Thanks anyway folks, spoken to Chris and going to give a good clean and tighten one of the belts. Hopefully that will work

Chris is the man

Best
Dave