I had trouble loading at first also, especially heavy rolls of banner material (new roll of 15 oz!) but I started sliding the roll holders all the way out and lay the banner roll right on the 2 bottom rollers, then lift one side then the other, I squeeze the ends in tight and leave the holder locks loose, then go around front and reach back through and slide it where I want.
I took a sharpie and marked the back of the plenum to mark where I want the roll to be so I usually get it right before I walk around front. It took some practice but I can reach back through and slide the rolls any time I want, the trick is squeeze the roll on the the holders so they don't pop off.
I also found you need to remove any media to cut after you lam the prints, one time one of the roll holders bumped my print an knocked it off its mark, the cut was off , I put it back in after removing the media and it cut fine, (the tech told me to leave the media in, I never left it in on my VP so I should have known better) I feel so far the machine is way more accurate and I find the prints are bullet proof to scuffing etc, ad the print speed and bright colors, i am thrilled so far.