Brian, you sound as if you are a person with a professional background in the technology of this printer. As you are offering some fairly detailed technical advice here I think it OK to ask about your professional expertise with this technology, or are you speaking from the experience of "informed and successful tinkering"? Just curious.
Hi Mark, I'm not an inkjet technician but have an electronics and software development background, my direct experience is with an Epson 7880 which sat broken for 8 months which I've restored to working condition.
Reconditioning required solving the current problems the OP has and clogged ink lines, replacement of clogged ink dampers, damaged CR scale and sensor replacement, replacement of all ink bay cartridge connectors, wiper blade replacement and required reassembly adjustments.
This project including study of Epson ink formula patents was carefully researched before work began.
I'm not advocating that frustrated owners with clogged machines jump right in and start tinkering; in the case of the OP he'd already started pulling the machine apart so I'm offering some guidance given my experience with my restoration.
You definitely need some technical skills or experience in disassembly and reassembly of electronic-mechanical machines or devices and the service manual.
Anyone without these skills (and patience) or with a machine still under warranty would be better served calling the makers service department.
Brian.