I'm sorry to hear you're experiencing ink drips on your paper during printing, and will try my best to help resolve this issue for you.
That is Epson's typical response, and if someone isn't using their inks- any issue they experience is blamed on the inks, no matter the actual cause. The 3800 and 3880 refillable cartridge system is one of our most popular products, and we have hundreds of customers happily printing with them for years. We also have a 3800 and 3880 that have been continuously used/tested with several sets of these refillable carts, filled with ConeColor Pro, Piezography and Ink Thrift- all with equally great results.
If you have been using our carts and inks in your printer for a couple months, and have had good results until suddenly ink drops started appearing on the paper during printing, then I don't suspect you're dealing with a bad cart or ink related issue, but have some questions to get a better understanding of what's going on, to help resolve this and get back to happily printing.
Based on the print example, it looks like one of the black or gray inks that is dripping (I don't see any color in the drips), though it could be a mixture.
1. Please remove the refillable carts from your printer and examine each one to make sure: A. the exit channel is at least 1/2 filled with ink, B. no ink is leaking from any part of the carts, C. there is enough ink in the cartridge body.
2. Are you having issues with all your channels fully/consistently printing on the nozzle check? Do you experience frequent missing nozzles in specific channels?
3. How often have you been using your printer vs. how long does it sit unused?
4. What is the humidity level in your printing environment? (yes- humidity can cause issues like this)
5. What paper(s) are you printing on? Have you tried other papers?
6. Is there any scuffing/scarping noise during printing?
Please let me know so I can help get you past this and back to happy printing.
Best regards~ Dana