I removed the stem and yoke to check and regrease and wanted to see how many balls are needed in case any had escaped :-)
I was surprised to see in parts book that balls are 1/4 inch rather than metric and there are 37 needed for bike.
I have been caught out many years ago on an old Triumph by fitting too many balls, so checked Haynes manual and different numbers required at each end with Top 18 and bottom 19.