My Color 550 is spilling small amounts of toner on prints. The awkward thing is this happens only on heavyweight stock. On regular paper prints look fine, but when I switch to HW 4 I get toner streaks. Mainly cyan, sometimes black. The developers are approx at 1/3 of the life, and their coverage is very good. The blades look good too. The drums are new. I've checked the filters but they look quite clean. I have attached a scan where you can see some of the toner streaks.