'96 48v burning up F/R Switch & No Reverse

[WelkeMS]

'96 48v CC DS. Batteries are 2 years old and have been individually tested and are ok.
Cart has a 2008 D & D Motor, 10.1 HP and 48 voltage.
Curtis PMC D.C. Motor Controller appropriate for motor.

When we bought the cart 3 years ago I replaced the batteries and it ran fine for a short time and then it would not go into reverse (sol would click). Replaced the F/R switch and it ran fine for about a year. Brought the cart home and added a lift kit, larger tires/wheels, new seats, lights, 48-12 volt converter, larger gauge battery wires. Cart ran fine, but was not charging correctly. I could not fit the larger wires through the obc so I bypassed it resulting in the charger not reading properly. I re-ran the old wire through there and that issue was resolved (unless I created a different problem.)

The cart ran fine, then ran in reverse but not forward....then would not run either way. Replaced the F/R switch again and it showed signs of melt around the connector. Ran for awhile and then same thing happened again, except this time it would go forward but not reverse, but the sol clicks when you push the peddle while in reverse. Also this time the reliance converter burnt up. Power read going in but not coming out AND the fuse did not blow.

Replaced F/R with one from CC that says it is "heavy duty." The cart runs fine forward, but will not run in reverse. We have stopped using it until we figure out what the problem is for fear of burning up another F/R switch.

Someone suggested it could be a bad speed sensor? I do not know how to check that.

It is incredibly difficult to find ANYONE in the area to work on it. Our local golf cart repair shop's only suggestion is 'buy a new one,' which we do not want to do. I apologize for the lengthy post, but I wanted to try and give as full of picture as possible as to what I've done to the cart. I am new to the golf cart repair world and appreciate any guidance you could give.