hi Oaksey
YOU DON'T LABEL YOUR YEAR AND MODEL = TYPICAL!!
I'm betting it is a pre-2004.
they suffer from the selector claw smashing into the selector pins very hard all their lives and the metal spreads with the non-stop pounding.
imagine two sheets of metal sliding on one another. then go up to the outside edge with a hammer and chisel and smash a 'V' in the edge. now the sheets catch on the chipped edges.
the answer is to dismantle the gear selector claw and using the outside of the bench grinder just chamfer the edge off the steel.
you can go straight to a 2004-2008 arm but there's really no need.
finally, if you have just ****** with the bike or it has never been right. go right back to basics. remove the claw and keep turning the selector drum clockwise, closkwise, clockwise while chuggin the rear wheel too and fro. keep doing this till the drum won't go any further clockwise. then go anti-clockwise a little and the neutral point on the selector star MUST be under the spring loaded wheel.
you've driven the bike down to first gear and then snicked it back a little to neutral. don't make it change in your mind to you. it must be down, down, down. first gear, snick back. neutral means that you can spin the rear wheel but hold the gearbox shaft in your hand.
Taffy