Gearbox Issues.

[Andjeti]

Alright I'll jot down everything that's happened then I'll pose my questions at the end.

I lost my licence for a month (For actually not doing anything wrong. It was for a toll charge back in 2009 that my E-Tag never registered when I went through). As such the ET wasn't driven for a month. I got my licence back last week and drove the car approximately 10Km to visit my sister. The next day I came out to go for a drive and the car was excessively hard to start and ended up with a huge back-fire out the exhaust, after which it started after a few turns.

I went to drive down my street and went through first-second-third and as I was attempting to change into 4th the gearbox would not engage. I decided to stop and check it out so I went back into third. As I attempted to change back into 2nd, it once again would not engage the gear so I stopped on the side of the road to check it out. With my foot on the clutch and the engine running I attempted to shift it through all the gears. It appears the gearbox has lost 2nd, 4th and Reverse while 1st, 3rd and 5th are fine.

No worries I'll just jump on the forums and have a look if anyone else has had this issue. I did a few searches and found that most replies were either a bent shifter arm or a buggered rear engine mount. I finally managed to get the car up on ramps today so that I could get under it to assess the situation and here's what I did. First I removed the shifter arm from the gearbox and the shifter and then I jacked up the rear of the engine and pulled the mount out to check it. The shifter arm is fine, the rear engine mount is degraded but not to the point of failure, however I still cannot engage 2nd, 4th or reverse by attempting to change gears directly at the box with no shifter attached.

I assume this means that something inside the box is stuffed as when I attempt to engage these gears it starts to engage and then seizes up and is real hard to get back into neutral. I have a spare box here, that I pulled out of the car when I first got it, that has a buggered fork on fifth gear and just keeps popping out. So my questions are as follows...

1. Can anyone think of anything else that could be causing the current box to not select 2nd, 4th or Reverse gears?

2. How difficult would it be for someone who has never dismantled a gearbox before, but is fairly technically minded, to swap over the 5th gear selector from one box to the other?

Thanks for any input you guys may have.
Jay