Welcome to JOF!
None of these parts are Jayco specific. Jayco only builds the shell, interior walls, and cabinetry. Everything else is from 3rd parties. If something breaks you may be able to upgrade it to something better.
I buy some things on Amazon, like a replacement outside shower, when it leaked because I forgot to winterize it the first year winter we had it. They carry the knobs too.
https://www.amazon.com/s?k=rv+shower...f=nb_sb_noss_1
Outside lights, brake parts, things like that I buy from Etrailer.
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Chuck
2013 Jayco Jayfeather X20 E (sold)
2016 Chevy Silverado LTZ 2 Z71 Crew Cab (sold, and dearly missed)