A method and apparatus for manipulating a surgical guidewire. The seal assembly includes a seal and a biasing device configured to produce a force for mechanically biasing the seal toward a first position relative to the rotatable portion. The groove WB has a depth Ds of about 140 nm\u2266Ds\u2266155 nm, the light-absorbing layer has a recess with a depth Dd of about 95 nm\u2266Dd\u2266105 nm in the groove, and a push-pull signal before recording has a value of about 0.