833 OD sticking in 4th, chipped synchro

Can you provide an update? Did rebuild cure the problem? I have the same problem with identical transmission. Only happened twice after prolonged highway travel. Transmission locked in 4th gear as I tried to exit freeway. First time it just popped out after about 15 minutes of me trying different ways to free up and second time It worked out after a few minutes. Its been almost 20 year since I rebuilt it but only 6,000 miles. I've been driving around town and had no repeat. Before I commit to a rebuild I'd like to know your results! Thanks