As we all know, the only way to flush or free a stubborn clog on the R3000 is to do an ink charge. If you have battery free chips, you maybe stuck because there won't be enough ink registered on the chip, even if you refill the cart.
Now, for my idea. If it is a bad idea, either delete this post or tell me right away. Could you install a 1mL syringe on the waste line for the side affected by the clog and manually apply suction? lf so, this could be a method to free a clog by suctioning just half the channels, saving the ink in the other half.