It sounds like the shifter inside the car is not properly synchronized with the lever that actually moves the valve body inside the transmission. Thus, when the inside shift lever is in "P", the transmission is actually in "N", when lever is in "R" the transmission is actually in "D", "N" is "2", "D" is "1", and "2" is pushing hard against the stop. Which is why the lever won't go into "1".

The parking pin is inside the transmission, and is what locks the transmission output shaft and stops the car from rolling away when you park it. One way you can test it is to put your shift lever in "P" and see if you can roll the car (hand brake off). If the car moves more than an inch or two, like it would roll down the street, then that further supports the idea that the lever and the transmission are not matching up, and that the car is really in "N".

I have not actually disassembled this part on an automatic, (my 850 is automatic, I haven't touched it on my 945, and my 245 is manual) so I can't offer details of how to check the linkage, but since that's what you had apart, I would re-inspect that for possible ways that it could have been reassembled too-short or too-long or misaligned or something.

Good luck!

Roger
'95 854T 256k miles
'93 945T 215k miles
'87 245 297k miles