I have 4x4 Cosworth, problem with the gearbox. I was driving normally, and suddenly I noticed that 2nd and 4th gear don't work. As I press clutch down, I can put the gears on, but as soon as I realease the clutch, gear stick will bounce to N. I've heard the MT75 box isn't very good so is it broken? I can still use 1, 3, 5 and reverse though.

Just addition: my viscous coupling is also damaged as the guy noticed in rolling road. Front wheels don't spin as much as they should. Does it have anything to do with this?

Thanks in advance.