Glossy Photo Paper keeps getting jammed ET-8500

A late response as I missed this, but verify the paper is within the weight limits of the printer mechanisms. Epson topload mechanisms typically have less pickup ability due to the limitations of being top feed; that said, these wide format units tend not to be plagued with that -- it's the desktop (8.5x14 max) models which can't be used beyond light papers. On this one, lighter papers run through the lower trays, and heavy paper through the topfeed mechanism. I'd still verify the weight as super heavy papers like high-end Red River paper may push the limits a bit more than you think.

If the paper is within spec, check the rollers for dust and wear—this will do it with glossy papers. If it is just dust, clean the rollers with a lightly wet cloth and then dry them off. Once you do that, rerun the paper and see what happens. Roller wear is a bit more complicated to fix in the lower trays. If the 8550 is designed smartly on the rear feed where the rear feed door has the rollers (and it's NOT part of the frame), you can replace the paper feed unit to fix it on this one.

If the manual is a clue, the ET- printers may have some smidgen of serviceability (which is a first for anything with inkjet, these tend to be disposable). If most feed issues can be fixed by replacing the paper feed unit (that said, the parts diagram shows some feed parts buried under the scanner requiring partial disassembly), then these newer wide-format units might be repairable. But I also am not holding my breath on desktop (8.5x14 max) models.