R380 noise from 4th to 3rd

[FarnhamStag]

Hi,
I've just about covered 200 miles since fitting the Rotrex supercharger to my 4.3 Rover engined Stag which is producing around 14psi boost at 6KRPM. Don't know how much torques its making but it made 280hp before charging.
The R380 box has started to make a tinkling noise as I change from 4th to 3rd, no other symptoms but does anyone have an idea of what it is.earchange hasn't changed.
Clutch also seems to be giving way changing from 3rd to 4th at WOT
so this will need dealing with too.

I would ideally like to at least be able to use the car over the summer and drive sympathetically, but I don't want to risk too much further damage or a breakdown hence the question on the gearbox.

Thanks, Dorian