The rod is secured with a self tapping machine screw (really just "nicked" threads at the beginning). If the hole(s) are damaged you might want to consider using some J-B weld (just enough to fill the threads on the screw(s) ) to make sure they remain securely in place. If you don't de-grease the threads they should still be removable at a later date if necessary.
Another method would be to remove the rod, rotate it one flat, then drill and install screw. If you choose this rout be sure and "lock out" the topper roller with a pin. This is installed at the end of the roller "hub" and passes through a hole in the shaft (not the rod you are working on). This will make sure your topper roller doesn't pull a "runaway window shade" trick on you.
Check YouTube for instructions or find the installation manual for the topper online. It will show the pin (which can actually just be a long finishing nail of hole size in the shaft).
"A wise man can change his mind. A fool never will."
"You only grow old when you run out of new things to do"
2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan