Hi Everett~
You can print from just the LLK channel using the QTR calibration mode, which will help purge the air from this ink line and damper without wasting ink in the other channels (which would happen if you did cleaning cycles). I have included instructions for doing this below.
PiezoFlush can be used with all printer models we support, but the print head cleaning kit can only be used with desktop printers that you can easily access the print head to clean (such as the R2400, R2880, 1400, R1900, R1800, etc…).
We have hundreds of customers happily printing with our refillable cartridges in their R3000 printers with excellent results. It is certainly not normal for inks to be printing well, then completely drop out. In my experience, when a position is printing well then totally drops out, this is caused by one or more of the following things: 1. closed air vent and is restricting ink flow, 2. cartridge not filled correctly (no ink in the exit chamber), 3. cartridge ran empty, or 4. some air from the initial cartridge instillation traveled thru the ink line and interrupted ink flow when the air reached the damper and head.
Prior to the VLM dropping out, did that cartridge run dry or very low, and was refilled- or it still running with the first fill or ink- or was it refilled, but the cartridge wasn’t empty or very low (still plenty of ink remaining in the exit chamber)?
Please let me know so I can help. We certainly want you to have the same great experience with these carts as our other customers using them in their R3000 printers!
Thanks- Dana 
Flush individual channel using QTR Calibration Mode:
To print from one specific ink channel (which is helpful when flushing just one line, without wasting ink in the other positions by doing power clean cycles), you can use the QuadTone RIP’s Calibration Mode.
Mac:
[ol]
[li]Open the “inkseparation8” image in Photoshop (located in Applications> QuadToneRIP> CurveDesign> Images folder) and select “Leave as is (don’t color manage)” in the Missing Profile window. [/li][li]If using 10.6 or higher, Assign sRGB to the image; if using 10.5 or lower Assign AdobeRGB (1998) to the image.[/li][li]Select the 100% patch of the color strip for the channel you wish to print (each strip is labeled with the color position) and make the entire image that color.[/li][li]Select the K7 version of your printer as your printer model then select the paper size you wish to print on in the Page Setup window.[/li][li]With Photoshop CS3 or below, select No Color Management in the Color Handling pull down list; with CS4 and above, select Photoshop Manages Color and the same document space as the profile (either sRGB or AdobeRGB) then push Print to continue.[/li][li]Change the Copies & Pages pull down list to QuadTone RIP. In the Mode pull down list, select QuadTone RIP Calibration (which will gray out the three curve pull down lists).[/li][li]Select 100% saturation if printing on scrap heavyweight, coated/print paper or about 50-80% if printing on uncoated, very thin or typing paper. Select the paper feed: either sheet or roll, 1440dpi is fine to select for this purpose bi-directional will print faster than uni-directional.[/li][/ol]
Windows:
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[li]Make a color flush image by opening the “inkseparation” image in Photoshop (located in the C> Program Files> QuadToneRIP> bin folder). [/li][li]Select the 100% patch of the color strip for the channel you wish to flush (each strip is labeled with the color position), and fill the entire image with that color- save the image as “QTRflush-color position”[/li][li]Open QuadTone RIP and select the paper size you wish to print on[/li][li]Select Tools> Options> Calibration Mode, which will automatically open an ink separation image file.[/li][li]Open the flush image by selecting File> Open (this image is a very specific RGB color, which controls the individual channel when printed thru QTR’s calibration mode)[/li][li]Select 100% saturation if printing on scrap heavyweight, coated/print paper or about 50-80% if printing on uncoated, very thin or typing paper. [/li][li]Select the paper feed: either sheet or roll, 1440dpi is fine to select for this purpose bi-directional will print faster than uni-directional[/li][/ol]