Gearbox/clutch problem

[Marshy]

Hi all,
Just got home from busfest and ended up with a gearbox or clutch issue, on a couple of times I couldn't find any gears but after I could select (or rather clunk) reverse I could get the gears. I now have a major grinding/squelling noise when I drive forward in first and wouldn't drive it anywhere, there is oil between the gearbox and engine.
Is the gearbox gone or could it be clutch?

 

[Trikky2]

Obviously it's hard to say till you strip it down but it could just be the release bearing or the fork.