A-833 Stuck in gear

Your answer is not clear. If the shifter is disconnected, you should be able to shift them. YOU MAY have a problem in the side plate interlock mechanism.

However, you may not be able to shift them with your hands. At my age and with my health problems, I probably could not, anymore. Put a small crescent wrench on the lever(s) and see if they shift. Also with one in each gear, one at a time, wiggle the other lever. It should remain in neutral due to the lockout