I disassembled the unit for the 32nd time (I've kept count) and used a length of filament that I cut off during one of the jams to determine the ideal printing temperature. By hand, I applied pressure to the filament until it began extruding. Interestingly, it got more difficult as temperature exceeded 155C. When I manually retracted the filament, I noticed it would catch when pressed back down, almost impossible to re-extrude. I used a drill bit to carefully clean the rig without scratching the heartbreak, little improvement.
Reading one of the other forums, I learned people have been applying a drop of olive oil to PETG with a lot of luck. Already having the head disassembled I figured it wouldn't be that difficult to clean if things went wrong, plus I have a spare of virtually every part.
What happened next surprised me. After applying the drop of olive oil, the extruder felt like I was extruding PLA. When manually retracting, the catch slowly resolved itself until it was completely non-existent.
I reassembled the rig with an aluminum tube around the Bowden tube to ensure the filament approached the head perpendicular to the build plate and began my test print.
Everything initially looked promising, the initial purge coiled into a perfect stack on the left front of the plate. Though the victory was short-lived, the print failed halfway through the first layer. I remain hopeful and restarted the test at 90% printing speed.