A walk power mower has a mower deck that encloses a pair of rotary cutting blades with the grass clippings from the blades being discharged through a rearwardly extending grass discharge tunnel in a rear bagging mode of operation. The mower deck has ground engaging wheels that are vertically moved up or down to adjust the height of cut. The height of cut adjustment system comprises at least one spring arm having a locking pin or tab that cooperates with one of a plurality of notches, detents or openings on the mower deck to select a desired height of cut. A threaded fastener releasably attaches the locking pin or tab to the spring arm to be able to replace the locking pin or tab without replacing the entire spring arm.