Boost if you've done this, or remember ...

@Natasha_Jay

Pencils don't work on head cleaners - you need 2 drops of the special cleaning fluid.

@arose62 @Natasha_Jay

The pencil is put in one of the two spools to rewind the magnetic tape.

@TCMuffin @Natasha_Jay

And head-cleaning cassettes had no magnetic tape to be rewound.