Called in today for new 540XP.
Good friendly service and a pleasure to do business.
Offered to fit the bar and chain for me and thinking they most likely knew more about the job than me I accepted. No idea what was wrong but on starting it threw the chain immediately it fired. Put it back on, same again.
Took it all apart and put it back together and all is good. No idea what was wrong with it either but it seemed to have a tight spot on the bar.
All good now, runs fine and cuts well. Thanks for your help but I will fit the bar myself next time.
Also bought a new penknife to feed my addiction. Proper chuffed with that as I have been promising to buy myself that model for quite some time.