First I'm not going to advocate this method of repair. It seems pretty solid, but it is a distinctly red neck git-r-done approach. I don't have the glazing strips to replace my window plexiglass so replacing the whole window latch bracket is out. I would also have to come up with a way to crimp rolled rivets to attach the new bracket. Actually I think fabricating a new bracket would be easier. It would just be a piece of 1 x 1/2 x 1/8 aluminum angle with a little dinking around to get it to size and shape. That said here is what I did.
Removed the glass and it's frame at the hinge, that turned out to be as easy as removing the center screw, lifting the window up until it stuck straight out and sliding sideways.
I used JB Weld to sister a 1/8 x 7/16 x 1 aluminum brace onto the stub of the bracket and extend the bracket stub with another piece of 1/8 x 7/16 aluminum butt joined to the stub. After the JB Weld was set (24hrs) I used a dremal to cut the two pieces down to just over 7/8 inch high followed by a little grinding to smooth it out and round the edges.
During the cutting and grinding I had a finger in contact with the bracket, when it heated up from friction of tool I used a wet paper towel to cool it off. JB Weld will tolerate up to 500 deg. fahrenheit but I know heat would be the most likely thing to weaken the joins.
I then drilled a small hole 3/4 inch up from the window frame, measured from base of bracket and re-attached arm using split rivet.
First picture shows the broke bracket after a little file work and dremal grinding to clean up the break, I also used a small wire brush to clean the bracket. The hole is left over from PO wire hook and/or attempt to attach arm to stub of bracket. Hey more for the JB to grip against.
This picture shows the brace that will run along side the bracket and the piece cut to butt up to the stub of the bracket.
This shows the pieces clamped on the bracket stub, with a small piece of wax paper between the clamp and the work. Wax paper prevents JB Weld from making my clamp part of the work when it sets. The lower clamp is holding the brace to the stub of broken bracket, top clamp is holding piece butted onto bracket stub to the brace.
When done it was already thicker by the 1/8 inch brace so I used the thinnest headed fastener I could think of to attach the prop arm, a stainless steel split rivet. No nut, one uses a screw driver to bend the tails outward then squeezes them flat with pliers. The tails were a little too long so I used the dremal and a grind stone to cut them off so the ends did not stick out paste the bracket. Purchased these at the local true value hardware store. Yeah hardware stores!
In the end I still had to file the slot in the window frame a little wider to let this thicker bracket plus rivet head pass through, but not much and it appears to be working. I can latch both sides of that window now.
While I was at it I replaced the rubber seal with 5/16 wide by 1/4 thick EPDM rubber self stick weather seal (in gray) purchased at Home Depot. This replaced the badly worn and coming unstuck white version of what I think is pretty much the same product. "D" profile but does not have the tab part that would go in the channel of the window, just sticks on.
I have two more of these brackets I need to do but I'm going to check the local hobby shops and see if I can get a piece of 1/16 inch thick aluminum to use for the brace. I think it will be strong enough and will then allow bracket through window slot without having to file the opening any bigger. If I have to I can get it on Amazon but dont really need 5 ft. for $20 bucks.