Is this possible ?

[Wondering_Mike]

My refill success with the 6210 was very spotty in that I could get between 2-6 refills before it was very difficult to get a successful deep clean. In that case I suspect it was sponge debris clogging the passages since the hypo needle had to pass into the sponge.

One thing i've seen when the top was of the cartridge was that you can refill the cartridge by letting the ink slowy seep into the sponge by applying the ink on top of the sponge. This way there is no 'debris' (which I doubt, but it is your observation so I will not contest it )

This method is rather slow but ensures a full saturation of the sponge. I personally use a sharp needle and inject 1/3 of the total refill load on the 'bottom' of the cart (through the sponge) , 1/3 in the middle (by raising the needle and then injecting) and 1/3 almost on top.

Good luck!