So the spool drops on the holder and then the worker pulls on the tape to get the parts attached to the tape. But the the spool spins from the weight of the tape ans parts hanging off. So is the spindle that sits in the bracket attached to the spool tightly or does the spool spin free on the spindle as well as the spindle within the bracket? I Was thinking about a rubber block in the bracket to provide resistance.. If the spool spins on the spindle then maybe some rubber grommets in the bore of the spool to provide resistance. The spool has a round indent near the center in the picture, if there are more of those evenly spaced, you could print the bracket nose a bit longer and incorporate a spring loaded rounded Nib (1/2" diameter or so) that would drop in the area and stop the motion. Adjustable spring tension would let you make it loose enough to pull without free wheeling...