No more 4th gear, Seems to be going into a false neutral Options

[zx-niner]

I don't want to admit it to myself but I think my recently rebuilt transmission already has a serious problem. The car shifted fine for about 300 miles then all of a sudden it wouldn't go into 4th when dowshifting from 5th gear. Initially it upshifted fine from 3rd but eventually that went, too. At first I thought it was my shifting technique since the car has been on jackstands most of the 3 years I've had it. Shifting slowly and deliberately helped at first. Then it started popping out of gear. Finally it simply felt like it clicked in gear but I got nothing. Whenever it felt like I got it into gear the shifter was"stuck" there and I had to pull hard to get it back to neutral.

A search of this forum resulted in possible causes of broken clutch tube or deteriorated bushings. I've had experience with both of those problems in prior 914s and there was a different feel to them, but it was worth checking out.

This morning I put it back on jack stands to investigate. I removed the rear shifter bar and all bushings look good. At that point I decided to manually shift the car via the small ball shift lever. At each gear engagement both tires locked in and could not be turned manually in the same direction. Each gear, that is, except 4th. No matter how I tried to engage the gear by moving the tires and slowly pushing the shift lever I got nothing. It "felt" like it engaged by solidly clunking into . . . something. But when it did so both tires still easily turned in the same direction. I was unable to move the shift lever further in hopes that it might be in between gears and additional movement would finally engage the gear. The range of motion into the false neutral was the same as the movement for engaging reverse and 2nd gears.

Does anyone have an idea what kind of failure would result in these symptoms? When Dr. Evil did his Northern California seminar I chose not to attend since I had this brand new transmission sitting on the shelf. After getting the car on the road and getting a couple hundred miles of seemingly troublefree driving, the last thing I want to do is start pulling things apart again. Granted, a transmission swap is pretty simple and I have the old one I used while this one was off being built. I am resigned to making the swap just so I can get the car back on the road. I would like some idea what might have happened and what it might take to repair.