Pics, as promised.
New garden trailer pin hitch and the new seat neutral safety switch adaptation of a 60A button starter switch from Advance Auto. As you can see, the PO reinforced the stock Cub hitch plate to handle heavy trailers with the ball hitch. My pin hitch is made of 3/16" steel, but I wish now I had made it of 1/4". Still, should be fine with the tongue weights of my little garden trailer.
Not shown, I used the seat bumbers purchased for my 1650 to set the proper height of the seat frame off the seat safety switch. Not shown, I also installed a DPDT toggle switch (on-off-on) switch so I can selectively bypass the seat safety switch. One direction the seat safety works, so that if my daughter gets off the seat the tractor shuts down. The other direction bypasses the seat safety switch, for when I'm dragging logs or trailers, or using the dozer blade, etc., when I want to be able to get off the tractor without shutting down.
Now I find the PO also bypassed the brake neutral safety switch, and when I looked at it, I found the lever that depresses the switch is broken as well. So, I have some more parts to order. Oh goody!