1984 Force 50hp I need basic advice

My 1984 Force 50hp - it ran fine except it wouldn't go anywhere. It sits there revving dead on the water no matter if in forward, reverse, or neutral.
Out of the water the prop spins freely in forward, reverse, or neutral positions. The shear pin is good.
I am clueless about the movements of the shift linkage on the powerhead - i.e. a couple of stop screws on parts that don't have a lot of movement when the shifter moves. I have not been able to find any kind of diagrams or youtubes that indicates how that linkage movement can translate into affecting gears down in the lower unit. I can't find it in two different manuals (in fact am having problems finding info that includes specifically the '84 50hp). I need to fix it myself.

I lost most of a short enough summer due to floods and closed areas waiting to try this in the water, and hope to get this thing going soon. Any advice I can get would be most helpful. Thank you.

The shear pin is for sudden impacts and keeping the prop in the right place on the shaft.
Inside the prop is a rubber hub that can let loose and the prop spins freely.
The rubber hub is installed with 20tons of pressure and sometimes it breaks free and needs to be replaced.
Most any place that sells or repairs boats or boat parts can get the prop rebuilt.
Or buy another prop??
Let me know if that helped???

Thanks jerryjerry05,

It turns out the shaft spins and stops in the right places so obviously you are right. By the time I got to it all the local boat shops (there are two) were closed, so I have to hope one of them has a replacement on Monday or else buy one online and wait. It's a relief to know I won't have to mess with the linkage or LU over this like I thought

You can put it in gear and try to spin the prop. If the hub is bad, the prop nut will not spin with the prop. If that's the case, Tim's Outboard in Hackensack Minnesota probably has a good used prop. 2186822331.