Hi all my beloved fourtrak gearbox has finally decided to start making some funny noises mainly in 3rd but you can hear the same faint knocking noise in 1st and 2nd, is it an easy job to rebuild? the gearchange is lovely and smooth always has been a bit noisey ( whine ) but been like that for the past 3 years so never really worried me gearbox level was always fine, be a shame to throw the box away, i have been given another box is there any way of testing this one before i put it into the car, i,d thought if it wasnt too bad a job i,d rebuild the existing one in my truck. Many Thanks in advance Dan