Series 3 gearbox problems

Hi i have a series 3 gearbox in my 80" hybrid. I finally got the engine running after buying it as a non runner project and now the gearbox will only move in reverse about a foot before it locks up! Going forward is better but it's not making happy noises so before i strip it any ideas what to look for apart from broken bits

Sounds like transmission wind up. Is it in low ratio / 4wd? Have you got the same tyres and diffs on front and back?

Hi thanks for the reply. It running the same front and back and the box was removed to do a clutch. I have not driven it more than 20m so don't think is wound up and that was in 2wd. I'm thinking it's going to want a rebuild so ill start looking for a spare gearbox to fit.

If anyone has one close to Northants let me know please!

What happens if you put high / low into nuetral will the rest of the box then operate correctly?

look at nut on rear of mainshaft

Forward gears appear ok but it has a grinding noise. Have not tried it in neutral but all the linkage moves freely now. I have found a good used box so that will get fitted and ill strip this one out to see what has gone!

As James says, look at the rear mainshaft nut. You may find that the tab from the locking washer has sheared allowing the nut to unwind.

Ok thanks I'll have a look at that tomorrow