F/R switch SPARKS only going into Rev-Marathon

[Mark59]

Had a friend(They rebuild motors for a living,not golf cart motors)take my motor apart because 1 connection on motor went bad-(spinning inside couldn't tighten it up or keep wire on securely,not enough threads left on outside of bolt to do anything with)When he got inside he replaced the bad bolt with no problem,replaced a bearing inside since he was already in there,and noticed 1 wire broken in half so he spliced it back together.When I reinstalled the motor( I had the cart's rear end off the ground) I tried it in forward seemed fine when I moved the selector to reverse I instantly got major 4th of July sparks coming out of the For/Rev selector switch.Scared the **** out of me,moved selector back to forward every thing fine.Rechecked everything I touched nothing found loose so I tried reverse again same thing major fireworks coming out of For/Rev switch.Put cart on ground drove it around in forward for 5-10 minutes all seemed fine.Took for/rev switch assembly off cart and found 2 of the 4 contacts melting so I bought another f/r switch and new contact board put everything back together still had the same problem No problem in forward soon as you make contact in reverse major sparks out of switch.Never had this problem before wondering if the guy that was inside motor could have reversed something inside motor?I've gone over my wiring diagram I made before I took anything apart I'am pretty sure I put everything back in the same order.Comparing my original f/r switch to the new one I already started to melt all the damage is happening on the same contacts/same position on switch & board.I must have a direct short somewhere but I'am not smart enough to figure it out.My cart has a metal body,2 seat back supports,no handle on roof/top,front has a plastic cap/cover at the bottom,I found this ID tag under dash on passenger side--79B25--this next section harder to read-I647I6.Guy I bought parts from said it was a 1979.I haven't been able to find a wiring diagrahm for a 1979 found a 1983 not sure if they match.Please Help me!!!It's a 36 volt system