Strange Aberration with William Optics FF/FR 6

[wuthton]

I was using a recently purchased William Optics FF/FR 6 for the first time last night and I've got a strange aberration which shows up on all the subs. It's worst with the green filter but present on all the others. I haven't quite nailed the spacing yet but I can't imagine that it's the cause. If anyone has any suggestions they'd be greatly appreciated.

I've attached an over-stretched green stack of 60s subs which shows it at it's best. Lots of streaky lines from bottom centre to top right.

[bogdog]

looks weird,had a play with image but seems its not on the glass? looking at the stars at the top close in with exposure upped

looks like the "scratch" is behind stars and not distorting them...but then again i don't have the best of eyes lol