How do I mend Pro1600pwa pressure washer cooling fan?

My (B&Q) Performance pressure washer (pro1600pwa) started making an awful noise after 10mins of working. I gave it a jiggle, then tried again. It started fine, then a minute later made the noise again. the pressure is still pumping hard, but it sounded like a bearing or similar. Anyhoo, I took the pump out of the housing and then took off the black plastic cover over the air fan. The plastic fan just fell out, leaving a metal spinny-thing poking out of the pump itself. There is damage on the fan blades and it makes sense that the noise was the blades spinning against the plastic cover. So I tried the pump again and it is as quiet as you like... but it has no fan attached to the bit that sticks out and whirls around... and stop me if i'm getting a bit technical... and it got a bit hot. The problem is that I can't see how to re-attach the fan back to the spinny thing. A gasket and a metal ring fell out with the fan but i see no discernable way of reconnecting it all together. Is there a simple reconnect, or do I have to take it all down to 'the man' to fix? thanks for any advice guys!