Hi there. Hopefully some of you very knowledgeable people can help me

I've been plagued by a leaky grouphead at the portafilter.

I changed the seal thinking that would cure it - nope... Tried a spacer to tighten everything up - nope...

What I have noticed is that the portafilter isn't centred on the seal and just clips the edge of the seal on one side. I have now tried locking it in the centre and it's a lot better but not perfect.

The outside diameter of lugs/tabs of the portafilter is 80mm but the diameter if the grouphead slot is 85mm.

Should the portafilter lugs be 85mm (ish) too?

p.s. It's nothing to do with the basket being too full as I'm testing it using a blind basket. Any excess pressure should get dumped. The pressure is spot on 9bar as I have an inline gauge in place.

That machine brings back good memories for me!

I have heard that it has the same head as a Silvia, and http://www.espressoparts.com/R_2931 seems to suggest that may be the case. (I'm not a professional servicer, so I can't say much more than "worth checking out")

Yeah - by all accounts it seems to be the same head. It doesn't make much sense that the lugs on the portafilter are 5mm smaller than the head - that's not exactly precision engineering...

Even a tiny leak means a drop in pressure - it's not the end of the world but beginning to annoy me now