The Ikon is a boiler machine, and the boiler needs frequent re-filling to steam the best. I never steam more than 100ml of milk at a time, so Im not sure whether the pump runs to fill the boiler while steaming. If it doesnt come on while steaming, the boiler is running out of water to steam and is in danger of dying of dehydration!
On most single boiler, dual purpose machines they recommend re-filling the boiler manually after steaming milk for two drinks.
Have you used the special tool to remove and clean the steam arm head, including reaming the holes?