Regulator Gears are Worn

I'm helping a friend get his house ready to sell. His front window, will open fine, but you need to pull on the window and crank the handle to turn. Looks like the gears on the regulator are very worn. I believe the it is a Minnkota window. It is a large picture window in the front of his house with 2 (left and right) side opening panels. I believe the windows are from around 1989 or 1990 time frame. I have attached pictures of the mechanism of the left window (from the inside looking out). Please let me know if you need additional pictures or measurements. Thank you.