I would ask management what exactly is the "Store Policy" in this case Shop Policy? Then you are clear on what you can or can't do.
I work with Gov/City employees, that don't do anything above and beyond thier job description. Even simple tasks, are left to those who do have in thier job description.
All I can say is work hard at your job. Show that you are capable and take pride in your work. Even though the other stringer sees you as a subordinate, see him as your equal for now.
Machines: Gamma 6004 2-point w/ Wise 2086 & Babolat Sensor Dual