Small spots on middle third of paper

I have a problem with small spots on an iGen3 in the middle third of max size paper and sra3. They look like a dot of toner with white edging round it. There are probably 30-40 on a sheet and are size of a pin head.
They are pre-fuser as panic stop shows them on unfused sheet.

Any ideas would be welcome.

Thanks

 

Any chance you could email me a digital picture? I've seen quite the variety of oddities on press. I'd like to see it specifically.

igen [AT] dailydigitalimaging [DOT] com

 

hi,

engineers have managed to track down the problem as low airflow through corotrons on two stations.

Seems to be cured apart from odd spot now and then,

many thanks