Re: 50horses forward
If you can start it in forward, then perhaps the linkage is mis-adjusted so that with the handle in neutral position, the lower unit is in forward gear. If it is that badly adjusted it is possible that there will not be enough throw to get it out of gear.
So, first remove the shrouds on the midleg to expose the linkage adjustment nut. If the threads on both shift rods are near the ends of their adjustment (more than say 1/4 to 3/8 showing) then it is quite likely that the shift is biased too far forward. Now, while a helper moves the control handle see if the shift rod moves at all. If it moves--even a little, it is probably free and you will need to adjust it. However, before you try to make any adjustments, try moving the lever on the side of the engine by hand as the assistant moves the control handle. This will pretty much tell you if the shift rod is stuck or not.
Moving the shift rod DOWN is forward gear. The adjuster is threaded right on one end and left on the other just like a turnbuckle so turning the hex one way will shorten the shift linkage and the other will lengthen it.
Because of its design and because of compliance in the system, If the lower shift rod is too tight, the shift linkage "gives" instead of moving the shift rod. If it happened to get stuck while in forward, you will not be able to take it out of gear
If it doesn't move, the lower shift rod is stuck--either in the seal which may have swelled, or in accumulated silt which tends to pack into the front of the lower unit like cement. If it is silt, simply clean it out. If it is a swelled seal--I pity you. On that engine, you need to disassemble the lower unit to replace it--a real pain
