I see you purchased a 4900 VM position refill cart and PiezoFlush. You can use this cleaning cartridge to flush ink from your VM line and damper, and hope PiezoFlush can help clear the clog.
The print head cleaning kit is different from what you have- and meant to be used directly on the print head to help clear stubborn clogging in the print head it's self. Most people try flushing the line with a cleaning cartridge, as you are doing, before dismantling the printer and cleaning further.
To flush your VM line and fill the channel with PiezoFlush, you have a few choices: 1. use QTR calibration mode to print from the VM channel to draw PiezoFlush thru the line until it reaches the print head, 2. Do several paired power clean cycles with the VM channel to fill the line with PiezoFlush, or 3. Do an initial fill cycle (which uses ink in all channels, so can be wasteful when trying to clean just one channel). I actually recommend the paired power clean cycles over printing, as cleaning sucks ink thru the head, and printing fires it thru using the piezoelectric crystals (which can wear out over time of use).
I hope this helps. Please let me know if you have further questions, or there's anything else I can help you with.
Best regards~ Dana