Digital BW, The Print

OK a rather simple question.  I am getting to my wits end with MIS inks/cartridges.  I don't 
think the issue is so much the ink "clogging" but the cartridges allowing air into the area 
around the spring valve over time if the printer is not used for a day or so.   Before I 
completely write off MIS I would like to try another brand of refillable cartridges - if one 
exists.