I received a set of refillable cartridges for an Epson WF-3640 printer. Based on my reading of the online faq's etc. it's not clear to me which hole is the refill hole and which is the air vent.
As looked at from the front of the printer, the back of each cartridge appears to be the end with the chip - it has colored, oblong tabs on the top and on the top front are round plugs. The front plugs look like they have the small plastic compartments underneath which would make them the air vents based on what I've read elsewhere on this site, yet the label on the top of each cartridge says "DO NOT REMOVE" right by the front plug.
Do any of these plugs need to be permanently removed for the printer to properly function in normal use?
If yes, which ones - the front or the back? And just to be thorough, could you please confirm which of these holes should be used for refilling the cartridges when the time comes?