I had the same problem,
The Shifter is probably loose as there are urethane bushings that rotted out preventing it from getting the full swing to the left. the shifter should feel fairly tight. I good snap to the left and up is required to jump to reverse.
Good luck with finding the water leak
If I can offer any assistance,I will try to help with as many questions as I can as I have a 67 200D Heck Flossen my self .
Regards,
Bryan