Question UV Ink Curing in strange places in machine? EFI H1625

I'm back with another issue I need help with. My H1625 has managed to cure ink 1) In the White secondary ink tank, 2) In the Black secondary ink tank and now 3) in the left side of the Cyan print head. I need some help to figure out why this is happening. Inks are all recent and have 6 months plus before expiration. Production room is air conditioned (kept at 73 during the work day - sometimes migrates to 77-78 if the day outside is over 95). Set to 77 at night. Room has blinds, all of which are closed 24/7.

The left white head doesn't see much use, but White ink circulation is turned on, and I purge all the heads 2-3 times every morning to get them all up and running. Most days will see a few purges throughout the day as well. 2 weeks ago, white (W1 aka the left white) would not purge. I flushed the head, it flushed fine and had a clean curtain. Tried to purge again, nothing. I began printing and saw W1's overflow line start to overflow. I stopped the print and tried to pull ink out of the secondary ink tank, no go. I took the top off of the secondary ink tank for W1 and it was slightly formed goo, fully stuck to the float (hence the overflow). I removed the tank and cleaned it out thoroughly with flush. Checked the filters (clear) and the lines going to the filters (clear).

2) Black secondary ink tank, this was Monday (first thing after the weekend). We printed Friday and cleaned up at the end of the day, no issues. This is the NEW secondary ink tank (installed 2-3 weeks or so ago). Half of the secondary ink tank was full of solid black ink - felt like rubber. I pulled the tank, cleaned it thoroughly, picking out chunks with a gloved finger. Ink inlet was wet and flowing fine, lines and filters were clear. The head flushed fine, no further issues.

3) Cyan print head (Not the secondary ink tank) - the left side was 100% cured this morning. I printed just fine yesterday at 5:15 pm, then cleaned the machine (Always wiping the foot with flush and a lint free cloth, then wiping each head back to front, cleaning the purge tray (same cloth and more flush) and shut down. Started up this morning, purged white twice, then color twice and went to print a nozzle check. Black had a little out and cyan was barely there. One more purge brought black to normal and magenta and yellow both looked just fine. Cyan was still barely there. I raised the head, clamped the lines and flushed the head, the right side curtain came clear in short order, but the left side didn't even drip. I let the flush sit in and tried again, still no drip. I cleaned the left side with a thoroughly flush soaked cloth and tried to flush again, nothing. I folded the flush soaked cloth and set it on some coro & under cyan and let it sit for 2 hours. Tried again to flush, no movement. I then disconnected the rear (for the left) filter and connected my syringe on the line going to the head. I opened the purge valve and was able to get some splatters of cyan through, along with what I would describe as coffee grounds of cyan ink out of the purge valve. A few more pushes and the flush would come out the purge valve as it should. I left the flush sit in there (also with the head siting on the flush and coro) for an hour. Came back, no improvement. I pulled and pushed the syringe with no movement. Why only the left side?

We've owned this machine for 3 years and have been using the same ink (STS) for the last year and a half. Until the white, we had not had ANY ink solidify anywhere. Help!

 

This is exactly what we found to be our issue. We had been using Nazdar flush for the last 2-3 years (Same container - expires 2020). It worked just fine with the OEM inks. Initially, STS inks worked fine together with the flush until they changed the formulations a few months back. STS now has their own flush. This issue ended up taking out the cyan print head completely. I had to have them come out and install a new head that I already had. When they came out and replaced the cyan head, I was having blockage in the right side of the black head. I began flushing the black head every morning and had a tiny improvement each day for about a week, but it won't get any better and is mostly unusable (we can print in RGB, which will go around most of the black printing, but anything requiring 100% k looks horrible.

I have reached out to STS to have them replace the black head (their cost), we will see what they say.

 

They sent their tech out to change the cyan print head that I had on hand last month, at no cost to me, so I have hope that they will step up.