Replicator Z-Shaft PreLoader
This is a plastic spring to preload the Z-axis guide shafts of the Replicator 1 against one side of each endplate.
In a recent teardown/rebuild of my build platform, one of the (several) observed reasons for its wobbliness was the presence of slop in the plywood plate that captures the bottom of each Z-axis guide shaft. On my 'bot there is no such slop in the upper plates... YMMV.
This little doohickey, once printed, may be wedged between the back plate of the printer's housing and the shaft, thus pressing the shaft to one side of its capture plate and, hopefully, eliminating at least one cause for build platform slop.