That's just a (spring loaded) ball detent or something like that. If it's internal to the valve, that could be a hassle (unless your tractor is still in Warranty). Unless you're mechanically inclined and somewhat familar with hydraulics, I suggest you leave that to your Dealer.
If you follow the joy stick down to the valve, you may see an external detent. Might be a pretty easy adjustment then.
Good luck!