Your L4260 screen shows: (Often error code 0x9A, 0x9B, or 0x9C). This is the #1 reason people seek the adjustment program.

No. The Epson Adjustment Program is Windows-only. You can run it via Parallels or VirtualBox with a Windows guest OS, but USB passthrough can be flaky.

The printer cannot be adjusted in normal mode. You need to force it into a low-level diagnostic state.

She had just refilled the ink tanks. The print quality was perfect. But the printer refused to do anything. No copying, no scanning, no printing.