i'm doing a valve adjustment on my t-100, and i can't seem to get any feeler guages in between the shims and camshafts. not one on the right side that i'm working on will allow me to slide one in. i'm doing it by whatever the haynes manual is saying. did it at tdc, 2/3 turn then another 2/3 turn. not even a 0.002 inch feeler guage fits in between any of them. could they all be out of specs by that much, or am i doing something wrong here? i've got 130,000 miles on the truck.