Check you clutch is fully dis-engaging
Could be worn sincros if never replaced
try adjusting your shift cables under your console, you will need 2x 10mm spanners, play around with them, more then likely if you havent got new cables they could of stretched really far by now. I adjusted mine today because i always had problems with 2nd any higher then 3000 and selecting reverse, 3-4th gear if fine tho. So just note that before you go and pull apart master cylinders and gearboxes.