I have 86 Moto4 225 that rarely shifts from high to low or reverse. When you actually get it to go into reverse, it usually will take over an hour to get it back into high. As you are trying to get it back in high you'll get it into low but then as you drive it will pop out. Eventually after playing in gear with it and lowering and raising the idle you can get it into high. Any ideas on what it is, or how to fix it?