the bracket 52 the first and second shoulders are aligned with the first and second flanges 62 and 64 in this position the roller housing can be slid onto the flanges of the bracket a flange 130 extends away from an end wall 128 of the roller housing 66 the flange includes at least one mounting aperture 132 for receiving at least one fastener 138 fig2 and 3 the fastener cooperates with the flange to selectively secure the roller housing to the bracket 52 it should be apparent from fig7 that the flange 130 is wider than the body 98 this construction prevents the roller housing 66 from sliding too far into the opening formed by the first and second bracket flanges 62 and 64 however when a flange back wall 134 is butted up against the edges of the bracket flanges 62 and 64 the flange apertures 132 are aligned with apertures 136 in the bracket 52 to allow the fasteners 138 to extend therethrough removal or replacement of a second guide member 90 is made simple by removing the fasteners 138 and possibly a cotter pin or spring clip attached on the axle end sliding the roller housing 66 out of the bracket 52 and removing the second guide member 90 from the guide track 32 this eliminates possible injuries to the user potential damage to.