high end distortion

just purchased a grado sonata. i am getting i high and mid band "vocal" distortion. i had the platinum and even though it was rolled off and not nearly as transparent i had "0" distortion. i set it up the same. if i increase the weight from 1.5 grams to 1.6-1.7 grams the distortion is subdude some, but, i still have it and i lose some air in the music. i had the sonata mounted on a previous basis setup with the same results. i thought it was because of the basis tt not the sonata. what should i do guys. is this just a sonic trait of the sonata? i have the lp12 with the ittok.
help ! please.
p.s. when they talk about the tracking ability of a cartridge does this equate to distortion ?
thx,tim