That is how the 37 -40 latch is designed .Line up the remote arm slot to the latch and then slip it in and turn it 90 degrees .It will not slip out. That pic I posted is off an EBAY listing so arms can be found although might have to be altered according to length or partially weld up the worn one and with a small file trim it.
Here is a remote on EBAY. You cand can cut and splice this on yours if that is easier for you.
https://www.ebay.com/itm/204460768721