You cinch up so tight & then it loosens?? Sounds like it's a horse puffing out prob. Perhaps doing the girth up gradually, one hole at a time with a break in between and ensuring the horse is relaxing when your tightening will solve the issue? That & perhaps not doing the girth up so tight.
I cinch up the way you describe, I never cinch up real tight at first, I always walk her around then cinch up again. I think maybe the saddle just doesn't fit properly. I have one breast collar but it is too large, I tried that the other day, but I may be able to add some holes and make it fit. But thanks for the advise. By the lack of response I take it that people think it's not the Pad.