Use OEM or Media Sciences (if you have to). MS sells under a number of brands - Tally, Boise OP, to name a few. Don't buy OLD MS ink (off of eBay, for example) - they're continually updating the formula.
Deal with MS directly and, if their product ruins your print head, they'll replace it for free with overnight UPS shipping (hint: that's an even better deal than Xerox, who will charge you $600+ for parts/labor if you're out of warranty, regardless of what ink you're using).
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