Spotting a gear box problem

[sarahandthebear]

Eavening all our van is currently in a garage getting treated to some much needed attention such as new fuel tank new water pump new collent pipes and of course it's going to set us back a few of the hard earned penny's. Our question is after all this work we would hate for something like the gearbox to go and leave us back In the garage again. How can you tell if your gearbox is on the way out of there is any way at all at the moment all gears seem to be selected fine a little hard to find but it's because it's a left hand drive and I'm getting used to using my right hand. Are there any ways we could prevent or even tell if we have a suspected problem before it gets any worse. We have a westfalia joker 1894 1.9 dg engine petrol 5 gears

[Aidan]

get the oil changed, see the drain plug magnet, refill with 75w/90 fully synthetic oil that meets GL4 spec, eg Smith and Allan on ebay and add a shot of molyslip GM6RA treatment, it won't fix anything but it will give you an idea of what's going on and the fresh oil and lube will help give you the best shift it can; go through the linkage as major wear there can give you shift issues
post up a pic of the magnet