I've got an old HRU214 that I'm tinkering with.
It drives in 1st gear no problem, but when I push the lever to 2nd gear, it will change gear ok, but it doesn't want to stay in 2nd gear.

There is resistance in the lever when trying to put it into 2nd, but it pushes the plunger at the gearbox ok & changes gear, but nothing seems to lock it in 2nd. hit a bump & the plunger pops out and it goes back to 1st gear.

Any ideas?