This is a strange one. Couple of weeks ago I was competing in a motorkhana. I wasflat out down a long straight and was in 3rd gear, tried to drop back to 2ndwhen there was a slight crunch. From there on all I could find was 4th and neutral.
 Normally when this is the case it meansthe gearbox is only working of the drive shaft  ie, serious problems. Now hear is the strange part. After getting the car home in 4th and neutral I then left it for a couple of days. When I next got in the car and started to wriggle the gear stick I found that I had 3rd gear back then after a while 2nd then 1st. I then took it out for a spin and at first the gears were a bit clunky but after a while all was well. What the hell is going on! I’m not ready to put it down to gremlins but the problem is now I can’t see the problem its going to make it that much harder to find it and solve it.
Any ideas

I suppose I should have mentioned that the car I was driving was a 95 SW20 3SGTE

Maybe hyraulic related. Does it drive as it did before now?

just that little bit clunky
 

Sounds like a shifter problem (internal to the gearbox).

That's my guess since its the most common thing to go on E153's.

Internal shifter issue would be my second guess.  First step would be a visual inspection of the cables, both lever end and at the gearbox.  If all's good there, you have full movement and you can see the external shifter levers moving properly then I would suggest DON'T DRIVE IT ANYMORE.
 
Contrary to popular belief, nano particle technology has not been fully integrated into todays vehicles, and mechanical woes do not fix themselves.  A worn or broken internal component means there are worn or broken bits floating around inside, waiting to be picked up and make a bad situation even worse.  Time to open it up . . .

Gearbox mechanic has had the car for a week and is also scratching his head. After draining oil and finding the oil like brand new. He checked all the linkages and cables. Then manipulated the leavers at the gear box. The sedition was to not pull the box apart but just to monitor it. It may just be I'm to aggressive with the changes. This weekend will tell as I'm entered in the TECCWA Red Mist Motokhana. Cross you fingers for me.
Ps. Maybe Nano technology does exist in ME2's

This is the order i would be checking things in:-
 
* cables, shifter rose joint, shifter bushes
* engine mountings
* block at the selector
 
If all that is perfect then look at the gearbox itself. You can bend selectors, wear synchs and the back of the case can sometimes break through the casing somewhat. Other than that these boxes are strong.

What do you mean by break through the casing?
All the external things there were done. Ill see how it goes this weekend

When I recently did the engine/box swap, I ended up with a very stiff gear shift.  Turned out to be an issue in the selector lever mechanism that is bolted to the gearbox (below the started), for some reason, as soon as I bolted this up, it bound the gearbox selector up and it became very stiff.  
 
undo the ends of the gear selector cables in the gearbox and and check the gear stick moves freely.  then try selecting gears by hand twisting and pushing/pulling the gearbox gear selector.   You can also loosen/remove the lever on the gearbox that moves the selector in/out leaving you with just the gearbox seelctor free, then try selecting gears again.  This will help you eliminate where the source of your fault is.
 
Cheers