can someone give a description of how to change the gearbox oil on an occy? perhaps with a few piccies?

No Piccies Im afraid

Car on the flat, as this is the way to measure the correct top-up/refill amount

description as viewed from looking at front of car

drop the plastic sump cover.

rh side of the engine (obviously on the gbox) is a horizontal plug. approx 15-17 mm across flats.

(halfords sell a gearbox plug removal tool or use an allen key if you can get a large enough one.)

unscrew this and drain the oil.

refill with vw oil or use a gl4 rated gbox oil (I heard that a gl5 rated oil is not best for VW synchromeshes !?) most of the aftermarket cans have a spout that accepts 10 mm plastic hoses. Best to pour it in from the top of the engine bay by the battery using a length of hose.

You can squirt it in from below but why make life hard.

When it starts to flow over the lip in the gbox its the correct level.

I think 2 litres will give you a full change plus some spare..

replace plug, to be pedantic you could use some ptfe tape, I find they don't leak if screwed back in as it appears to be a tapered thread.

doh,

usual typo,

there are 2 plugs 1 to drain and 1 to fill, but you spotted that already I guess.