If you're getting forward and reverse, you MUST have neutral there somewhere as the clutch must go through the neutral position when going from forward to reverse. Has the shift linkage been monkeyed with? There are detents that may now be misaligned.
Prop could also still be ticking over in neutral simply running on friction between one of the gears & the prop shaft.
Not unusual in my experience.
With the motor off and neutral selected is the prop free to turn?
