I just unboxed an 1810 and when you use
the document feeder, it has a gray
background on one side. This happens
intermittantly. If you lay an original
on the glass, this never happens-only when
using the document feeder. I would appreciate any suggestions!

Hate to be the bringer of bad news, but
check the DH to make sure its level to the glass, front to rear,
then, if that doesnt work, call your regional rep and have him adjust the CCD. If you do it, the claim will be you messed it up.
Been there, done that. New CCD fixed it.

DON'T mess with the CCD.

When you run copies off the glass, check to see if the scanner returns home all the way, or if it 'bounces' back away from the left side about 10 mm or so. If it seems like it does, remove the glass and manually move the scanner to the home positon area and see if it does the same thing. If it does, check to see if the scan cable mounts on the front and back side of the machine are level or are sort of slightly nose diving. If they are pointing slightly downwards, very gently with a pair of needle noses tweak them so that they are level. This is most likely your issue. Haven't seen it on an 1810, but have seen it on 1510's(multiple). Good luck!