Following on from this topic:
Our 3880 performed flawlessly for 5 years but recently we started seeing blotching and contamination of prints. I attempted to wash the capping station with spray-and-wipe cleaner but the fluid was not draining from the left-hand pad. I opened up the printer housing and removed the whole cap unit, then dismantled the little pump. I was able to flush the crud out of the tubes using a syringe with warm water and detergent - see photo attached. Now our printer is again working beautifully.