I was having trouble fitting the valve collets and the valve seals (the tiny O
rings) when it struck me why!

The valves I am using only have a single, narrow (<2mm) groove in them and not
the larger groove I've seen before and as are seen in the various workshop and
parts manuals.

Presumably these types of valves don't use a valve seal?? Is that right?? Are
they going to be more prone to leaking than (what I presume to be)the more
conventional type?

Thanks

Greg