Besides, I had to have the shift linkage fixed and the shop was able to verify that the gearbox is in fact sticking in fifth and the car needed to be "rocked forward" to pop it out. That's why letting the clutch out while decelerating against the engine allows it come out of gear.
How does reverse engage when you select it?
Any noise at all as you move it into reverse gear?
Considering that it is only sticking in fifth and not all gears and no one's complaining about having to refill their reservoir, I would say that's not a real great guess.
Hydraulic leaks don't have to leak onto the ground to fail. If they go past internal seals the fluid stays in the system but doesn't operate the system.
Have you ever seen someone pump their brakes to build pressure to stop? The brake fluid isn't going on the ground, it just isn't pumping up the brake cylinder at the wheel because of leaking internal seals. Pump fast enough and you outrun the leaking internal seal and the brakes work.
Not all gears are the same... the ratios, tooth pitch, etc. can affect how each gear engages and disengages. They wear at different rates as well... in the 020 trans, 5th is usually in good shape if it hasn't been ran low on oil, while 2nd is usually beat up no matter how much oil is in it. The gap between ratios (from 1st to 2nd or 4th to 5th) are not the same, so the wear is different.
The point is that 5th can act up but not the other gears. Reverse can be a problem by making noise on selection but the rest of the gears can be fine. 2nd might grind on fast shifts while 4th is fine no matter how fast you shift.
In the end I would say his guess is worth at least what you paid for it.
If nothing else, he was the only one who took the time to reply to the thread you brought back from the dead so while you may not think it a good guess, it does look like it is the absolute best response you've gotten, his guess beat out every other guess you were offered
