There are 4 rubber pieces, one at each end of the of the fabric, two in the tube, and two in the trailer rail. The ones in the trailer rail should have a small screw securing them to the rail, so the fabric will not slip on the trailer side. The ones in the tube, should be touching the end caps, so the fabric can not slide in the tube.
For alignment, don't mess with caps on the tube. They are installed with steel rivets and must be put back that way. On a warm day, unroll your awning for a an hour or so. Now roll it up, and see which way it is off. Take the crews out of the track on the camper, and see if you can slide the fabric. ( there may be sealer in the tack making this difficult.) Roll, and unroll a few times. If this works, reinstall the screws in the track, and you are done. If this still doesn't work, you can loosen the two bolts at the top mount for the awning arms, and slide them a little, the bolt hols are slotted left and right.Hopefully you can get it aligned up and rolling straight. Don't forget to tighten everything back up.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT