Gear Leaver

Hi..can anyone please advise me if you can purchase the small pin
that is thru the bottom of the gear lever. The one on our bus is
worn as it appears to have got stuck in the hole in the end of the
leaver. I presume that the pin should be free as it has a spring on
it?
We are haveing diffficulty selecting gears..we have fitted a new bush
to the end as this was missing and also need to replace the selector
plate as that also has some wear in it.
Many thanx for your time