I recently changed my head 9/10/2018 , It's on a Roland VSi 300 . When it was new the prints were flawless ! I could do my grey to black gradients absolutely perfect , Now I'm getting the cyan overspray and my gradients are just awful and pink .. First ( stock head ) worked GREAT for 5 years but died shortly after I switched to 3rd party jetbest inks. I just came to this conclusion the other day when I was thinking about it.
So is my thought process correct ? my test print is perfect , colors are good , gradients fail but are perfect with a new head.
Honestly, having an OEM head last 5 years is possible but most manufacturers will say average life is about 2-3 years. So I wouldn't necessarily jump the gun and say the ink was the culprit there. The new head dying within such a short time is very strange. A bad head could be the result from many variables...ink "could" be one of them, but there are others to consider.
As a user of JetBest inks for over 7 years on our Mutohs I have a hard time believing it would be the ink, so here are some other things to check...
1. What are the condition of the head cables. Over time, they get coated with a mist of ink, which can eventually eat through the insulation and cause shorts. The same thing can happen when you change a head, and not knowingly kink or crack a cable and with a little time it cracks enough to develop a short which will cause misting and overspray as you are describing.
2. Where did you get your head from? You realize they make a water base and a solvent base DX5 head? Many folks have been ripped off by buying a water based head off ebay or some other vendor which will last a while and then basically fall apart from the solvent eating through the head.
Just some other things to think about...