Just bought a 93 flagstaff pop up and having problems with it staying open. Of course when we looked at buying it, it was already open and there are no problems closing it . Anyways... when opening it, it slips on every crank also making a popping noise. It feels like it is tightening as it is being cranked up and then pops. It slips while trying to open it but after a few tries eventually will stay open. We were able to get it fully open and tried cranking it one more time; it stayed up but didn't fix the problem Has anyone had this problem? Any help would be greatly appreciated.