I'm having problems with my 1972 100 hp Johnson. This is my first boat I've owned and I'm having problems geting it into forward. After playing for a while (popping from neutral to forward) I can eventually get the prop to stick. It usually ingages and them pops back out after 5 secs. Is this a problem in the shifter or maybe the lower end? Reverse is strong. However, it once continued forward when I pulled back into reverse. Help I'm confused. Shops can't get the motor to duplicate the problem. How can I resolve this problem?