Thank you all for the prompt response – I do have that manual thank you Michael.
The bearings sit between to flat shims which are about 1mm thick. They do not have machined grooves in them but there is some surface pitting. I have already worked out that these could be reversed if needs be to provide a decent surface for the balls to run against. Some of the balls are pitted which is why I said they are worn. I get the impression that the oiling point on the traverse may have become blocked.
A quick Google yesterday showed a similar product that is called a thrust bearing and with similar cages.
Dimensions are: Outside diameter 32.75mm and inside diameter (the hole) is 19.30mm. As I said earlier I am pretty sure that this mill is mainly imperial unlike my 1978 Boxford lathe which is a real hybrid of Whitworth & metric.
Thank you all once again for your help which is much appreciated.
Regards, Nick
PS: Graham – just seen your post.
Edited By Nick Thorpe on 28/07/2015 19:05:22
Edited By Nick Thorpe on 28/07/2015 19:05:45