Gearbox jumps out of second gear

[allencr]

Can it be easily held in gear or does it try & pull you out of your seat?
2nd gets a little different wear then the others cause it's always for accelerating, it gets slammed because its a straight pull, it's easier to pull then push when accelerating, and people are almost always pulling on it a bit, before & after the shift, even though they'll say they aren't. The extra wear is on its dogs/teeth and on the fork.That's for long term gradual wear and then it still really takes a lot of abuse besides normal wear & tear to do this to any trans.
If this has just happened suddenly, it's something else, usually lever related, a plastic bushing on the selector's bottom has come apart or some stray bit is limiting its travel.