Need Help Suggestions Simple issue: paper curl from roll while printing

I have what feels like a very simple issue that probably has an easy solution the veterans have figured out.

Oftentimes rolls of certain types of media (particularly glitter and printable HTV) curls UPWARD when loaded on the machine, causing the print or cutting head to strike the paper on either side.

This can sometimes lead to a catastrophic failure, jamming up the motor and causing a hard stop, ruining the material in the process. Does anyone have any techniques to get the roll to rest flat or curl away from the head? I've resorted to literally standing at the machine while it cuts/prints, holding the paper edges down while dodging the head as it passes until enough material has fed through it holds itself down!

I'm about ready to just get some alligator clips on strings with weights and just clip them to either side of the paper while it's working!

 

Thanks for the tips, everyone. Part of the problem may be I don't have a take up reel - the business I'm at has sort of just swung from the hip for the last 7 years and doesn't really have all the tools to do business the right way, so I'm the first employee to come along and actually try to do things the right way I'm basically working with what I've got to make things work! I have switched to the long media clips on the SP-300i in question and that helps (had to make myself a warning magnet not to use the cutoff!). I may just use the weighted gator clips just to keep things smooth.