T25 Jumping Out of 2nd Gear?

[DibDub]

A family friend has an F reg, 1.9, water cooled T25 and they are wanting to sell it(£2,000), only found out today after taking a drive to see another van (long story).
Anyway, it has no tax or MOT, very clean, no rust and low mileage. However there is a problem, apparently it pops out of gear when in 2nd. Only in 2nd gear. The battery is dead so I am going back to see them in 2 days to start it up and have a really good look at it.
I've searched the forum and found a few threads with the same problem.

What would be the best way to go about getting the gear box sorted?
Rebuild?
Replace?
How much would either option cost?

Any information would be great, I think the van is a good price but obviously not taking into account the cost of getting the gearbox fixed. So I need to know the best way to go about this. Thanks

[Aidan]

4 or 5 speed ?
rebuild from £645/£675
used from £150/£250
new £2000-3000+

[dbz864]

if you want it rebuilt aidans you man,theres a chance it could be your front gearbox mount cheap and easy,is it a 4 or 5 speed.just for interest is it a camper or van

[DibDub]

4 or 5 speed ?
rebuild from £645/£675
used from £150/£250
new £2000-3000+

I'm not sure if it's 4 speed or 5 speed, is the price much different between the two?

if you want it rebuilt aidans you man,theres a chance it could be your front gearbox mount cheap and easy,is it a 4 or 5 speed.just for interest is it a camper or van

Yes I was reading about the gearbox mount but I wont know until I get a proper look at it. It's a camper.