The roller on the window guide attached to the bottom of the window glass may break off and cause the window to come off track.Google+
Car Problem Reports
Pontiac Firebird Roller on window guide may break
Pontiac Firebird Problem
Average Mileage: 130,000 mi (80,000 mi - 179,000 mi)
Visitor, 1999 Pontiac Firebird, 80,000 mi
thought it was the guide / not motor..but but the whole assembly..put it in..got the rollers inside the bottom of the window chanel..and that roller that is revited on the window bottom..that goes up and down the rear guide..broke off the rivet..omg...now finding that whole assembly is impossible..all i need is a new roller and see if i can bolt it on..rediculous..screwed up the regulator bent the one roller piece..and it really pissed me off as i could have hammered the old one out also..the motor and regulator were just replaced 3 yrs ago..
Visitor, 1997 Pontiac Firebird, 98,000 mi
had a friend repair it - BOTH windows!! Driver's side took a couple of repairs!
Visitor, 1996 Pontiac Firebird, 163,000 mi
mount brackets loose