I have a customer some distance away from the shop that is telling me that their C1020 won't let them make copys off the glass, indicating that he must use the ADF.

Anyone know why this might be?

It would really help to know what model copier this is occuring on at least, since a C1020 points towards "Lift Motor 2 Error" on a Voyager "E" series and most other color models. This error I don't think has anything to do with copying from the glass or the document feeder, I would, however look into the possibility of a broken lift motor. I have seen several broken "Old" style motors on the Voyager series.

I believe he is referring to the FS c1020 mfp

Yes, it's an FS-C1020MFP, appologies for the confusion.

I have not seen this but a few suggestions which can be done over the phone is the scanner lock on maybe?? or maybe has something to do with 2 sided copying ??

Probably not. The DP on th FS-C1020 MFP can only scan single sided, not duplex, even though the MFP can print duplex. =^..^=