833 OD sticking in 4th, chipped synchro

I too read this post with great interest as I was having a similar problem. I pulled the trans and popped the side cover off and sure enough I had a strut sticking up when in 4th similar to the OP.

In the end, my issue was the strut springs, they were oddly shaped and not making good radial contact with the struts. The spring popped off the strut in the middle of the spring on the 4th gear side allowing the spring on the input side of the syncro to rock the strut up when in 4th and make it a pain to get out of 4th.

I had a parts trans so I grabbed all the strut springs from it, plus 3 struts. The other 3 struts I replaced with new parts from Brewers. I also got my gaskets and countershaft seal plug from them. All my syncro's looked brand new, the trans had been rebuilt and had less than 8-10K on it, so I left those as is.

Trans works great now, no issues since putting it back together.