Well problem solved, turned out my clutch cable was just hanging on for dear life when I removed the handguard, it was a miracle it hadn't snapped to be honest,
new cable fitted and adjusted properly and the gear shifting is perfect again, it was nothing to do with the linkage being worn, but I lubed that all up anyway so that's it sorted,
must remember to oil the clutch cable and grease round where the lever pivots at least once a year in future.