I found this
web page possibly related to your problem.
Try their troubleshooting steps to see if you have a failed brake switch or a failed brake shift interlock solenoid.
If the plastic lever is broken in the shifter assembly, then look at their video.
The YouTube video from that page link has no sound, but in the first 40 seconds the video shows the mechanic freeing the stuck shifter by pulling off the shift knob and striking it with a BFH.
Hope this helps.
Edit: Advice does not apply, I forgot you have tumbler issues as well. It is probably best to let the tow operator use their expertise/tools (towing with dollies under the rear wheels or a plastic glide under tires when winching it up onto a flatbed).