In reply to mike kann:
Thanks Mike. I was just questioning if it was a defect as all my other Master Cams have them, even the 00, and it just stood out like a sore thumb. And, if I didn't ask I would always have a wee niggle in the back of my mind when making marginal placements.
Metolius have been very responsive and have just replied:
"No need to replace your existing cams with grooves, they are fine. We made this inline
change so we could relocate the cord hole thereby strengthening the cam stop
location. It's not a "safety" issue, just a fine point in manufacturing detail. The grooves
on smaller cam lobes don't do anything anyway, they're just for appearance."
Hopefully this may help anyone else with the same concerns in the future.