Sensor Replacement or Removal in a Safewatch Plus RF?

I have an ADT "Safewatch Plus RF" alarm system and one of my "Sensor 9" module has gone wonky.
Is there any place I can get a replacement for one of my sensors? Or program the unit to stop reminding me it is not working?
It's NOT a low or dead battery issue as a working battery from another unit and a fresh battery failed to fix the issue.
(I have other safeguards installed in sensor 9's position till it is fixed. ;-) )