Squirrels in the 961?

Good morning all,

i finally achieved a 'one day' dream and bought a 961 mark 2 his week. I love it despite its foibles but it does make a very strange squeaking noise from the engine: like squirrels in rusty armour fighting inside a cooling radiator. Can anyone advise if this is a Norton normality or if not what should I be checking? Many thanks for any help and apologies if this has already been covered elsewhere.

Cheers,

Rick