Well, from what I've read, on the older Falcon, if the capping station isn't kept super clean, like the rubber ring around the edge can't seal then you can also have a vacuum leak problem.
When you ran the cleaning solution, did all the lines run clear and into the waste tank? Supposedly the power flush wastes a real ton of ink and solution. Your waste tray or bottle should have filled up considerably. If it didn't I'd still suspect crusties in the lines under the capping station.
I made a device that I can hook up to a Vacuum Pump that wraps around my print head with a silicone gasket. Made it on the CNC Router. Anyway, when it gets real bad, I'll use that to prime the print head instead of drawing such a heavy load on the puny little built in vacuum pump. I don't waste as much extra ink either.
Sometimes when you get air way up in the lines it's almost an impossible feat to get all the bubbles out, and you end up with an ink starvation issue that also leads to clogged print heads. That's a $1200 dollar mistake I don't want to make again. Always pull ink and air through the dampers with a syringe. You have to kinda tilt the damper upside down so the air bubbles go towards the hole where you have the syringe.
If you ever get cross mojination with the yellow, you almost have to throw away the damper. Because even a little bit of cyan or black can muddy up one or both of the dampers, and your profiles will never quite be the same. You can do a pretty good job of trying to purge the ink with the syringe method at that point, but what I've done is just carefully pulled the damper off completely and ran some cleaning solution through it, then pre filled it with some yellow before I attempted to hook it back up.
Careful, when you pull the lines off the dampers, you introduce air to almost the entire ink line all the way back. Keep in mind that will have to be pulled out through the damper, as it's got a one-way valve to keep air form going back in. When you see ink creep, it's time for new dampers.
