Wont shift into Forward?

[sublauxation]

I've been restoring all summer and starting to get things put together. A couple nights ago I tried out the controls and it wouldn't shift into Forward.

I took the cable off at the control and the shifter worked just fine.
I took the cable off at the engine and the shifter worked just fine.

I tried shifting the lever on the engine and it wouldn't shift.
I had my son turn the prop and magically everything worked just fine.
I put it all back together and everything worked just fine until my son tried it again last night, now it wont go into forward..
I've never had a problem shifting into reverse.

Is this some sort of problem or is it just that sometimes gears mesh perfectly wrong in an engine that isn't running?

 

[sublauxation]

I should probably add that it's a 90hp Etec with a side mount control.