Tape the glass with duct tape if it is broken or cracked.
Hold the glass with one hand, or have an assistant hold it for you, and unscrew the set screws on either side of the window pane from the metal wedges. Remove the wedges, which look like L-shaped brackets and wrap around the window.
Slide the glass out carefully.
Measure the glass to find a piece that fits it exactly. This glass is thicker than the average glass, so ensure that your measurements are accurate. You can also take the glass in to have a similar piece cut.
Slide the new glass back into position. Place the wedges over the glass edges and screw them in place with the set screws.
Remove the glass from the window.
Insert the head of a screwdriver into the hole in the stay bar and work the stay bar pin out. The pin needs to be shifted out from behind a piece of metal so it can pop out.
Unscrew the operator from the window frame and remove it. The operator is the operating mechanism that opens and closes the window -- often it's a crank or lever.
Position the new operator on the window frame and work the pin back into position.
Screw the operator to the wood frame.
Reinstall the window glass.
Remove the glass from the window.
Open the rusted rivet hole using a 2mm drill bit. Work the drill bit carefully back and forth in the hole to ensure that the hole is wide and clear. Avoid damaging the window frame.
Insert a 4mm rivet into the hole using a rivet gun. Ensure that both metal pieces of the operator are lined up before you insert the rivet. Pull the rivet gun's trigger to release and secure the rivet.
Replace the window glass.
Oil the rivet with machine oil, such as that used for bicycle chains or sewing machines. Oil all the rivets in the window for good measure.