i am guessing a few things to look at
what had you done just before this started.
air leak on joints
recirculating pump failing look for ink on the gear wheel of that pump
return ink line blocked so as the pump tries to recirculate the ink it pressurizes the cart,
have you used a syringe on the white system before this started and pushed in stead of pull.
poor batch of dampers cheap ones ? but would expect the other colour used in that damper to fail as well.
when removing the old damper you left a seal behind.
This all started when when we had trouble with the whites printing, we would do a clean and then hour later the nozzles would be clogged. I figured the damper was shot, print head was only 6 months old if that. When I replaced the damper that's when the leaks started. White is the only one leaking, cyan is fine.
It sounds like a damper issue if leaking.
Better yet, if not a cheap damper (3rd party), did you place the damper in backwards. What is backwards - opposite the other one. The direction really does not matter, what matters is that they are all in the same direction. As chris stated, ensure the old Oring is not left in the well. Prime the new damper when inserting it.