Double image/double cut

[NickWL]

I've had this before but can'r or the life of me remember how I cured it:
After a major cleaning session I'm getting a cut and a faint (but noticeable) 'shadow' cut about 2-3mm above the main cut in the y-axis.
The head is not moving to make this cut so I have to assume it's a reflection of some sort.

I've done the following:
aligned the mirrors
cleaned mirrors and lenses
reseated the lens
changed the lens for a cheap K40 original
reseated the air-assist housing.

Nothing I do seems to work... am I barking up the wrong tree?

HELP please!!
Nick

[Tech_Marco]

Check the lens, it could be lose
Check the light beam alignment as it may hit the laser tip at the far end.

Marco