A friend is helping me clear some land. He brings over a 580C from maybe 1975-1980 and clears about 3 acres, pushing over mostly small oak trees and juniper here in Central Texas. It was going strong. Then he loses reverse. He wants to get a new transmission (before learning how much they cost) so I suggest Lucas Transmission Fix because why not? So we put in 24oz (after removing an equal portion of old dirty oil) while it is warm and he gains reverse and loses forward. It will do forward a little bit while pointed downhill, but no power. At this point he's not convinced it is the transmission and thinks it may be a control module or gear box. I think he should change out all of the transmission oil and filter. Does anyone have any clue what is going on here? Anyone have any videos on rebuilding the transmission? Cheers.