GT transmission problem

[dobigl 0]

Hello everyone, I have posted on here before about my GT 14 that my uncle gave me. I took it in to a small engine place and they told me it loses reverse when it gets hot and to junk it. I was advised by this site to change the fluid and filter ( and not to go back to that small engine place . I did that but used oil instead of dextron (thought that was alright as I did read it here 10W-30). My son and I have taken the tires off and some of the fenders to make it easier to work on. I have changed the oil drained the gas and put new in. It runs good with a jump as it needs a battery. It now sits in my garage and I am struggling with time to fix it. My plan was to get it working again so I could use it. I live in southwest michigan and was wondering if there is anyone in southern michigan or northern ohio or indiana that would be willing to complete the fix it if I brought it to them. Thank you for any advice....George