An error recovery technique is used on marginal nonvolatile memory cells. A mounting plate interfaces with the vertical support, while one or two support plates are supported by the mounting plate and by anchor elements extending through each of the plates. A controllable device for generating a negative pressure is provided on the belt for the purpose of retaining the work pieces on the belt. 5% by weight, based on the graft base, of graft branches. Each of the spring retainers includes a plurality of projecting portions extending from the base portion. The junction box is provided with two opposed open ends, one of the ends being in alignment with a side of the ballast housing and the opposed open end being adaptable for electrical communication with a lighting fixture.