The original design is flawed so the parts will fail regularly usually at an inconvenient time like a rain storm.
Replacing saab window rollers.
A big pita to replace.
Using junkyard glass and doing it yourself can save a significant amount of money.
Although the instructions will not tell you you must lubricate the parts for the window to function.
Replacing the window glass in the front door is a very simple repair.
Typical junkyard cost is 75 for the front glass vs 375 for a new window put in by a glass repair company.