Prima F30 not burning properly?

Hey, I've got a Prima F30 that starts up but after 5 - 10 secs the flame doesn't seem to burn right.
It loofs like there's turbulence disturbing the gas jets.
Result is flame isn't burning out of every one of the ports in the mantle? Does this make sense?
Colour of the flame looks fine.
After about a couple of minutes the reset button pops out and it cuts out.

Any ideas?

Cheers