Honda Fourtrax 400 - gear issue

Dear brains trust,
I have a Honda Fourtrax 400cc 2005 model,
I bought it off a guy, and it doesn't select reverse, nor drive in lower gears, seems it's stuck in top gear so easily stalls. He said it was "an easy fix"..

Just looking for advice, I'm pretty handy at fixing most things, so knowing what could be wrong is what I'm chasing info on, just don't know alot about quads.

Keen to get it going properly to use on the farm, so any info in appreciated.


Thanks in advance.