Loading plastic reels usually boils down to two issues - sticky slots or ball bearings, and not being able to get the film aligned while getting it into at least the first 2/3 of a rotation of the reel.

These days I use Jobo reels, so there are no ball bearings, but the balls must move freely on Paterson reels. Running some cloth and possibly graphite along the slot can help, and definitely do not put wetting agent on the reel - dump the film out into a jug for that.

The reverse crimp on the end of 120 film helps me load, too. I was told that by someone I used to know, who was told about it by someone else, probably all the way back to George Eastman 8-). Make sure you get the film aligned evenly at the start. It ought to push onto the reel for at least half a turn. I also leave the film on the spool and just coil up the backing paper as I go.

I still have the odd film that seems to be particularly malevolent, but I usually win in the end!