So I ended up applying three bits of advice from thise thread

I went to the loft, thanks Paul, they kindly replaced the cams.
I shaved a bit off the cam ends, thanks nauli.
I used a ~25cm tip extension, thanks Bender (and 2ndWind).
Now it rotates consistently and sets sweetly. BTW it also rigs and rotates well on an old Arrows Lance 430.
Great advice from the community and great support from local retail and manufacturer.
Looking forward to the weekend.