This invention relates to a novel screening method that identifies simple molecular markers that are predictive of whether a particular disease condition is responsive to a specific treatment. The base plate includes a back wall defining a pair of latching beams and a blocking tab, and a front wall defining a receiving space and retaining finger. The depressions are preferably formed in the area between two o’clock and four o’clock andor eight o’clock and ten o’clock on the racket head. A rotatable brush pressed against the abrasive cloth is rotated about an axis substantially perpendicularly to the plane of the abrasive cloth, and oscillated substantially radially between radially inner and outer positions over the abrasive cloth. An expanded bristles section loosely contains the bristles portion of the brush.