Douglas
I feel your pain. However, I'm mo' lucky--mine only locks up when I'm not really watching what I'm doing and then only when trying to shift into reverse. Be aware that the 3-spd column shift has historically had a few problems like you are experiencing.
Have you spent some time with a friend operating the shifter while you look at linkage points to see if you have too much slop or?
Have you opened up your "shifter box" under the hood to see if you have excessive wear or maybe a lack of lubrication or mud dobber nests, etc.? Just opening it up and taking a look while someone slowly shifts will help you understand how it works and perhaps give you some insight if your problem is there.
