Well with the weather being crap over the last few days I havent had chance to test ride...
The grumble grumble noise has completely dissipated, all I can hear from the sprocket side of the bike is....the chain going around the sprocket....
Ps.. the chain, bike is new to me so I have no way of knowing what "real" life the bike lived, It was looking like a shed tho' so I could see the chain dying prematurely...Bike has 10,000 mls (uk)..
Threre seems to be two settings on the bike reference to the chain..
45mm slack, good feel from the gearbox but the gearbox whine is loud...
55mm slack, clunky gearbox but the gearbox whine has nearly gone...
Thankyou all for your advice, ride safe and good luck...tosh