G620 - no red at all

[WaldportTech]

Hi:

Very nice, G620 printer, been fine until recently. No red is printing. Magenta, cyan, yellow, black and grey are fine on the nozzle check. The lines for "R" are blank, as shown here 

I have done cleaning, deep cleaning, and flush. Did the flush multiple times as that's the answer I kept getting from the internet, but it has made no difference. 

And, yes, the red resevoir has plenty of ink in it. 
The red tube appears to not be empty. 

What else can I check, test, do? 

Thanks for any advice you can give me. 

Appreciatively,

Phil

[DerrickL]

You may need to manually clean the left print head.

[WaldportTech]

Thanks! I'll give that a try. I hadn't realized the print heads were so simple in this case. I'm used to more complicated ones. I'll let you know.