Thanks for the encouragement.
However, running Service Diagnostics on the Carriage Assembly gives Error 02.1:10 "FAIL reading Pens voltage."
After a long talk with Sr. HP tech, he says it could be just PCA, but if spend a full day to tear it all down, should at a minimum replace the entire Carriage Assembly (Q6659-67019) which cost $1,100-$1300 new (although eBay may have for $500, if it can be trusted), and possibly Carriage Flex Cable(s) at $80 each. HP auth service tech estimates $1500+ in labor. That could take up to the $3K realm, with little/no warranty if the next thing breaks. The Canon 4000 is down to $3500, the Epson 9000 $4,000 (plus extra ink, etc. etc.) and has warranty.
Two years ago, I went through replacing the belt, and it was a three week elapsed nightmare with a technician -- it is not a trivial fix.
I hate to keep pouring good money after bad. Most say I should be thrilled to have gotten 9 years of service from it.