How to Fix loose Clutch on Hayter 26 mower?

Hi,

A Friend's Hayter 26 Roller propelled Mower has a very loose clutch assembly. It appears that the clutch bearing, and similarly the Clutch sprocket are held in place by a securing ring. The part numbers are 2238 and 2239.
Can anyone assist with such parts, or advise of a supplier who may have such items. The rings appear to be some sort of ribbed shim, but we are unable to locate any such similar material for this fix.
Thank you