Pull your shifter out and check the ball and cage on the end of the actual shift lever. If it is worn out or the bore that it goes into is worn then it will not full disengage from the syncros on each gear. I am taking a shot based on what you described, but it doesn't cost anything to look and only takes about 5 minutes. If it is worn out then you can probably get a new shifter set up for a whole lot less than a tranny and a lot less work too. -Ed
Havent been on in a while but I seen you were looking for a trans for your pre! I have a 5 speed that I just pulled out that I can sell you! It is in great condition! Converting my to automatic, so the 5 speed is up for grabs! Holla at me if your interested!