No Maintenance Tank

Someone gave me an older Pro4000 printer with refillable carts that I’ve been using with no problems until recently. I went to use the printer after a few weeks away and 3 colors wouldn’t read. After being unable to get these to work (all 3) I finally ordered 3 new chips. After installing the chips, I still couldn’t get those three to read. So I give up for a while. A week later I try again. Voila! All carts reading… except… now it says “No Mnt Tnk”. I tried resetting. A different maintenance tank - nothing.

What gives?

Check out the connector of maintenance tank, mabye you have ink leak there for that cause intermitent reading on cart because is in aame bus of data, put it out and clean it