Removal: You need to make 2 cuts on either side
of the crank using a hacksaw. Then bend the frame back with a pair of pliers.
Undo the mounting screws and pull out the window crank (gear box). You
will then need to take the crank to an RV shop where they can match it
to a new one.
Installation: Do the reverse!
After you bend the frame back, you can solder the cuts (difficult with aluminum?); however, this isn't really necessary because once you put the screen back in place, the screen frame will cover the cut marks.
This was contributed by Chris Demerah:
To change the window cranks I had to remove the windows from the the
trailer and disassemble them. There are about 20+ screws that hold the
windows in. The screws go from the outside through the aluminum window
frame, then through the fibreglass and into a wooden frame on the inside.
The wooden frame is covered with aluminum on the inside. So, you have to
pop off the black plastic strips on the outside of window (mine were mostly
degraded from the sun) and simply remove the screws. Once the window
is out, there are eight screws that hold the frame together, I took these
out (spray some WD40 or penetrating oil on them). There was a couple of
snap rings holding the shaft on, you have to take those off.
I tried to get the gear box out without all this dis assembly but I could not see how to do it. (I don't think you can). I found the matching gear box at an RV parts shop. I also bought a roll of the putty tape that is used to seal the windows and the roof vents.
I ended up replacing the wood that the screws bite into because it was rotten and I used Stainless Steel screws to put the window back in.