asterisk users - Jan 2006 - Received fax "offset" in tif file?

Hi, all -- some (but not all) of the faxes I receive on my Sangoma card
have an "offset," where the right 3/4 of the fax are shifted left, and
the
remaining portion is "pasted" on to the right edge; see
jots.org/~ken/fax.jpg for an example.

Anyone have any ideas on how to get this working?  Since I'm using a
Sangoma T1 card, I tried out using ztdummy as a timing source (as one page
recommended), but it doesn't seem to have made any difference.

Thanks!

-Ken