This is the part of the video used to transfer drive to the
cassette reel spools. It swings from either the supply or take up spool
depending on the direction of the tape.
It is used in the
Fits between the two spools
It is often prone to seizure causing the tape to jam in the machine
or the fast forward and rewind operations to perform badly or not at all.
When the unit fails, a complete replacement is needed. It cannot be fixed.
The unit is cheap and relatively easy to replace. Unfortunately the part
is no longer available from Sony.