These are all very valid questions and the answer is not exactly direct or straight forward. Lets 1st get a good base line of the situation, which sounds to me may be different then just a clogged Vm channel.
For the read out of the chip level for the VM cart, this is unusual. Yes, it should be reading 1/2 full after performing the Ink Charge (because that is the amount of ink the printer uses for this procedure). Even if the Vm cartridge is actually FULL, possible due to a clog, then it should still read 1/2 full like the rest of the cartridges. Lets start with these questions:
- If you run a cleaning cycle, does the ink level move on the VM cart? Or stay Full?
- Leading up to this have you noticed the VM ink level staying Full or automatically resetting itself?
Normally if there is a faulty chip on a cartridge you will get a Cartridge error, this would be if the battery was dead. If the cartridge levels are reading full on the printer panel, as well as on the Status monitor through the printer utility this points more towards printer chip read sensor read outs and not cartridge itself. Although anything is possible! I would for good measure, replace the battery on the VM chip and see if that changes the reading capacity of the printer. So, replace the battery and run a couple cleaning cycles to see if the ink levels change on the read out or if the VM comes back.
It sounds to me like the printer is not pulling the ink from the VM cartridge possibly due to an electrical error internally. There is still the possibility of clogged head, damper and/or capping station, but at this point you need to get the VM cartridge ink levels reading correctly to diagnose this problem. Once there's a diagnosis we can offer a solution for a fix.
Before going through all that I would give the printer a good thorough cleaning following these video instructions http://shopping.netsuite.com/s.nl/c.362672/sc.42/category.122444/.f