Is it possible that string type, tension and gouge can make a difference with the shoulder problem only wile serving? I have tested ProStaff Tour 90 demo racquet prestrung with Wilson Extreme 15 string (don’t know the tension). Only wile serving I have some shoulder pain. With my i.Prestige MP with Head InteliTour 17 string (24k tension) and I don’t have problem with shoulder pain. Is it possible that when I strung Tour90 with the same string as my i.Prestige MP the shoulder problem will be solved?