My Tohatsu 6 4-stroke is becoming hard to shift. It happened once and I couldn’t get it out of forward. The next morning it was working fine again. It is now about a week later and it is difficult again. It says in gear fine. It still shifts but with a lot of difficulty. Forcing can’t be good. Service manual says check 1) detente ball; 2) shift rod; and 3) clutch. Any thoughts on how to check without disassembling?