A follower mechanism movable along an axis within a bore including an alignment groove. The follower mechanism includes a bucket with a cylindrical inner surface and a cylindrical outer surface, and a yoke positioned at least partially within the bucket, the yoke including a bottom wall and two opposed sidewalls depending upwardly therefrom, each sidewall defining a shaft aperture. A shaft with first and second ends is received in the shaft apertures, and a roller follower is rotatably received on the shaft such that a portion of the roller follower extends axially outwardly beyond the bucket.