Back to Ever See One of These?
8-Track Tape Tension Checker
from an eBay ad:
"The last users of 8-track until just a few years ago were the DMV to record Motor Emission Inspections and the Rail industry to record train fuel level, processes, etc.
The quality of the tape had to be tested first to insure good recording quality. A poorly tensioned tape will not play correctly. Old tape players not correctly aligned may also distort the 8-track tape tension.
This unit can help a serious tape collector to accurately identify which of their 8 track tapes have tension problems. "
Crazy! Who knew such a thing even existed?