Disco 1 Gear woes....

Morning gents, I completed my drive to work the other day and drove home, reversed into my space, went to take her out of reverse and it was stuck in gear, I "persuaded" it into neutral but it wouldnt wiggle left or right or select any other gears, I could simply put it either into reverse (which successfully would reverse) or straight back up into neutral, my friend has had a look and managed to force it into gears so it moves but says it appears to be a new gearbox, does this sound about right or could there be another problem causing this? What checks can be made to confirm this as I'm hoping for a simpler fix? He told me on the phone last night of 3 things he had checked before he drew this conclusion but I was rather inebriated and the info is pretty foggy (something to do with a "bias plate?" and also some form of pin that was ok when inspected, sorry its a bit vague but I can ask him again when I see him in the next day or so).

Also if it turns out it is a new box what would be the best course of action to take, I prefer to do something properly and do it once, even if the initial cost is more, I've been offered a second hand box for £150 but am worried I may have the same problem again in a year so was looking at "ashcroft transmissions" at £495 are they worth the extra money (or could you recommend another option) also is it worth adding the HD rear support brg? at the same time what else is worth replacing? clutch? that little rubber seal that always seems to fail and lets engine oil seep out of the whole where the engine and gearbox mate?

Apart from it recently being occasionally ever so slightly more difficult to engage gears (almost unnoticeable and wasnt sure if it was just my driving) there has been no warning signs of any gear problems, no whirring, nothing, the only thing I could report and it could be unrelated was she seemed to be a little juddery if I was reversing in low revs, or sometimes whilst driving in low gears with low revs, raise the revs and the juddering went.

Out of interest has anyone got a rough ball park figure for the labour for fitting a new gearbox if its worst case scenario?

Thanks in advance, and sorry for being pretty vague, I can find out more info when I speak to my mate.

Just thought I should add, its had the same clutch and gearbox for at least the last 8 years (approx 50/60k miles- total mileage on vehicle 160k).

First of all check the gearbox oil level, drain the box and check for metal particles in the oil, this will confirm or otherwise a major failure within the box.
You may find your gearbox problem is just a failure of some component of the gearshift mechanism, remove the centre console, drill out all the rivets that hold the transmission tunnel rubber gaiter section in place. You will then be able to remove the gearstick. There are a couple of nylon bushings on the stick, one at the pivot point and one at the bottom, all of the bits connected to the gearstick must be in place and adjusted correctly to properly enable the gears to be shifted.

The clutch actuating arm on the Disco 1 has a design flaw which means it won't last for 2 clutches. If your clutch was changed and it wasn't that could be the problem. It happened on my 200Tdi years ago. Removing the gearbox to change the clutch is not difficult but it is a lot of work and made a lot easier if you have access to a lift rather than trying to do the work with the car on axle stands.