I'm guessing optical sensor?
Duct tape keep printing if it will let you
thats what i would do..but I am by no means an official tech...I am used to there being a backlog of jobs and making it work until there is time to properly fix it...
If you have time or money do a close inspection and/or hire a tech...
Post a thread asking for a service manual for that model..someone will email it to you.
just rig it in a way that it won't fall and hit a printhead <---most important part of rigging these things
It senses the end pinch rollers to tell the machine how wide the media you have loaded is. You need to re-attach it if its not broken or replace it if it is broken. If its not in the correct spot or not working you wont be able to set up any media.