Any ideas on why my LSWSelect360 prints all but a No.10 envelope?

I'm printing from a LaserWriter Select 360 via a G5 through to AsanteTalk to my MacBook Pro (2 year old) out of InDesign. Airport Extreme is in there somewhere too. I was a bit concerned that the old LSW wouldn't be supported when I updated to Mavericks, but all seemed to be fine. Printing 8.5 x 11 pages from the tray isn't an issue. However, I can't seem to get a No. 10 envelope to print correctly via the manual feed tray.

The manual feed tray centers the envelope in the middle of the printer feed area, but when it's fed through nothing is printed on the envelope. I did a test with an 8.5 x 11 page fed through the manual tray and the printing is occurring at the right side of that page. If the manual tray fed the envelope flush right, I wouldn't have a problem.

I did create a custom preset for a No. 10 with all the settings, sizes and appropriate feed in place. But it's still not printing through the centre of the tray area. I'm working in InDesign CC, but have tried this with CS6 and out of Acrobat as a pdf as well.

This only became an issue when I accidentally turned off my G5. Usually it sleeps peacefully beside my desk until I wake it up for printing. I did reconnect everything via AsanteTalk and printing has been fine – with exception of the No. 10.

I'm wondering if a default driver is somehow overriding my preset and although I've searched, I can't seem to find where I could change that. IF that might be what it is.

Any ideas?

Thanks. Sandra