Roland sp300v print issue

[fwgrafix]

We recently picked up a used Roland SP300v to be used in conjunction with existing SP540V, Had Roland service tech put 2 new print heads in and all seemed good, until we print blacks. We are using Flexisign Pro and Production Manager, if we print a black made up of 74.9% Cyan - 67.8% Magenta - 65.5% Yellow - 90.2% Black - The black looks good like a true 100% black, however if i choose to print a black that is 100% black it looks like a charcoal dark greyish/Brown. The 540 puts out all other colors very very close to the 300, But the blacks or any shades of black is way off, The print test looks great, Any ideas. Since the tech is not all that familiar with Flexi he is still looking into it, and figured I would try to find a solution as well