Grazing Muzzle Rubs

Berdi has been using her grazing muzzle for about a week. She finally got the hang of eating with it and loves it. However it is rubbing her on her jaw quite bad. I put fleece in it and pads and it is still rubbing. If it gets any worse I'm afraid it might bleed. :( Do you have any ideas of what I could do to stop the rubbing? I've tried vaseline too and it just hardens on the fleece and rubs the more. Any advice would be much appreciated!

Hi
I put 2 of mine on gm. I was told they just have to come off periodically to avoid the abrasion. So I have a two fold plan to attempt to get weight off of 2 way too fat horses. Good luck!