I apologize for my rudeness, in not answering you right away. Also, I appreciate your checking. Meanwhile, I have reached out in several directions; the problem(s) are possibly in an improved state. I refer to the Epson ET-4750. Yet another example of several possible causes, hardware or software, drivers or wifi. And actually at least two distinct problems: scanning had become impossible; and the problem with long jobs crapping out and restarting. Ideally, one would change one thing at a time, until he ruled out at least a number of potential causes. However, desperate flailing, in a confounded state of mind, leads one to change any and all possible factors and hope one of them was the culprit. As I have done. Perhaps, if issue is solved, the other one will as well.
For one thing, I have reinstalled Manjaro i3 on a different partition. I also hooked up a USB cable. I had fooled around with the ppd file, and looked for ways to tweak settings that are not visible on the CUPS Web portal to localhost:631 (which I erroneously referred to a a "GUI" previously).
I posted to the Manjaro Forums, and received a couple of answers. Sinisterbrain had this interesting insight:
"As I understand how printing works. The system/CUPS will send pieces of
the print job if there's not enough memory in the printer or if there
is, it just sends the whole thing. Either way the printer will break
the job into chunks and print them"
Perhaps useful, perhaps not.
After I discovered that the USB cable was plugged in improperly on the printer side, and connected it, finally, a few boots later, a hopeful message was received:
Bus 001 Device 008: ID 04b8:1129 Seiko Epson Corp. ET-4750 [WorkForce ET-4750 EcoTank All-in-One]
Since that time, I was able to scan a document with the native Epson tool "utsushi". However, neither gscan2pdf nor simple-scan detected the scanner. Even when simple-scan was run as root, no luck was to be had.
This new Manjaro setup somehow ended up with normal printing order as the default, where reverse order was the default in the other Manjaro. A long document printed through to the end, which is hopeful. If this is a solution, this may imply one of at least three different changes have solved the issue. Maybe more... fine with me; unhelpful insofar as resolving the root cause. Fingers crossed.
During the meantime I had written an email to Tomas Pospisek, who had posted information on OpenPrinting.org about at least one similar printer, telling him that I had found the USB id for the ET-4750, in hopes that this might help somehow in speeding the development of a specific driver. In that letter, I had mentioned, as an afterthought, my problems. Surprising to me, he answered with some extremely useful information:
- I'd guess if you run out of space in your /tmp or /var or /home
partition, then printing might break.
- Also, if you are regularily updating your Linux installation (or it is
regularily updating itself), then something might have broken in mid-way. [This informs me that some of the instances of my updating kernels resulted in a non-bootable system, as I had suspected.]
For now, I am holding back on any further pursuit. There are some hopeful signs.
I plan to edit the config files of sane and the bizaare driver from Epson that Epson will not support. Maybe if the hardware issue is suspected I will contact Epson Support.
My apologies, and my thanks. Very few would go to such lengths to correspond with anyone on such an issue as fuzzy as this one.
I am in awe of the breadth of your knowledge and your kindness.