So, the saga continues ....
Pulled the MS appart again today to reveal exactly the same problem as last time, a lump of brass embedded in the graphite rotating half.
After cleaning up, this is what was removed, note the score marks in the brass, static half.
On inspection the brass washer which sits between the spring and the 'O' ring in the graphite seal half was slightly chewed up and rough with sharp edges. Similarly the ends of the spring were quite sharp. Given the state of the washer I could only assume that the brass fragment lodged in the graphite came from here. That said there's no reason for the washer to get chewed up ... everything on the rotor rotates with it!
Anyhow, I decided to replace the brass washer (which was quite soft) with a steel item, so one was turned on the lathe. The edges of the new washer were broken using a wire wheel on a bench grinder. The ends of the spring were gently re-flattened on a grindstone and the external edges slightly champhered. The edges were then given the same treatment as the washer. Again the two halves of the seal were sanded and linished.
These are the components which went back in the pump.
I tested it for a couple of hours this afternoon and not a leak in sight ... Ooo, that strange feeling of deja vous.
If this lasts I'll update the wiki page. I think it's tempting fate to do it straight away!
