Digital BW, The Print

Has anyone found a way to clean used CFS carts to use them with a new
ink? I know MIS says just to buy new carts but I've developing a
collection of color carts.  And they're not cheap. 

I have a set of MIS CFS color 1280 carts that have FSN-E in them
sealed away in a baggie. I'm using CFS carts with UT in them now and
want to try UT2. 

I hate to buy prefilled carts to try as they're not that much less
than a set of 4oz. bottles of ink.

Bob Michaels