Let's be very clear on what you are telling me: You said: "When I use pliers to move the shafts the prop does go into neutral and then into reverse." You used the plural of the word shaft, did you really mean just one or more than one and if so which other?
Assuming you meant a singular shaft, 1 each, and that 1 each is the shift shaft stub sticking out of the front of the LU that was in your 1st picture. Is that correct?
Then you said: "But it always wants to go back into forward". What changes? Does something happen after you have gone through N to R? I assume you let go of the shift shaft with the pliers. Is that correct? Can you see it, the shift shaft, turn back to where it was before you turned it to where you got N and R gears?
Come back on that. I'm 8:22 CDT. and I see your light is on so you are either on her or left your computer on this sheet. I'll wait.
In case I miss you, if your answer was yes, then do the following: Get your pliers and turn the shift shaft until you can make the shifter go into N and R again like you said you just did. Carefully, back up through N and on back to F but don't go any farther than you have to in turning back toward F gear. Keep one hand on the prop as you are turning the shifter shaft and as soon as you feel the prop lock up, or start clicking, depending on which way you turn it, stop turning the shifter shaft.
Put the remote control in F gear with throttle full advanced. Carefully reinstall the LU and pull up a couple of nuts to hold it in place. Now place your shifter in N. Did the LU shift to N or not? If it didn't Chinewalker was right. If it did, you are good to go, button it up.
Remember when shifting into R the prop needs to be turning to ensure the cogs and pins line up. Don't force the remote into R without rotating the prop by hand if the engine is not running.
