Thanks Dan and allon...
There is some agreement re the slots and to act as a relief / vent... But if it was critical, one would expect to see it else where, thus why ?
And if it did make a difference to the cup, what not then market the feature. But could find nothing on it. Mind you google it not always able to find exactly what you want / ask for.
Allon, if you don't use a basket.... Then teh slots are deep enough that the lip would need to bite at least 4mm into the group seal...
I think I will just need to did out another 4 or 5 PF and try them all. ONE MUST FIT
Mark
Ability is nothing without opportunity. - Napoleon Bonaparte