Thanks Bob and Andy,I knew I had seen a thread regarding the conversions,Bob,but could'nt remember where!It will be useful to refer to should the replacement muffs need modification.Yes,Andy,the bearings do have a recess on the inner face,though they don't seem to be quite as deep as those on the Shop 3 illustration(though that might just be my failing eyesight!)I understand from Jon at shop 3 that the replacement muffs are on their way so I will see how to proceed when they arrive,
Again,thanks,Ian