Has anyone else experienced this?

[1HTBRRD]

I recently could not get my T56 to go into gear. A friend suggested changing the gear oil, but I insisted the oil had only been in the transmission for less than a thousand miles and could not be the culprit.

I eventually changed the fluid and poof, the transmission worked properly again. I bought the transmission off craigslist and I know it had been sitting outside of the car for awhile....

Has anyone else had this problem? I'm curious to see if I'm driving on borrowed time and should be expecting to rebuild this transmission soon.