Help! AB Dick 9850 Envelope printing

I'm pretty new to printing offset on this AB Dick 9850, only 2 years. Never had a problem like this printing envelopes. When printing them the flaps are opening and creasing. I noticed that the flap is opening before going into the rollers and creasing.

I've tightened the guides up, I've loosened the guides. May clear up for a while, but boom, back to doing it again.

I'm ready to push the press into traffic!

Any ideas?

Thanks!!!!

Lou