There are many reasons why audio cassette decks require repair and maintenance. It could be that the deck no longer works or that the sound quality is no longer clear. When these problems arise, it is essential to clean and check the main components. This is not an especially difficult task, but it does require a little tape deck knowledge.
Dip cotton swabs in Anhydrous isopropyl alcohols and gently scrub the heads, the metal fixture at the bottom of the cassette dock that reads the tapes. Dry the heads with a dry swab.
Turn on the deck top spin capstan--the metal spindle to the right of the tape heads--and gently wipe an Anhydrous isopropyl alcohol dampened swab up the capstan shaft.
Clean the pinch roller--the black rubber roller that guides the tape--by rotating the roller with a clean, alcohol soaked swab. Clean the stationary metal and plastic guide posts.
Wipe all these parts dry with a clean, dry swab.
Plug in, or switch on, the demagnetiser away from all audio equipment. Slowly move the tip of the demagnetiser towards tape heads. Slowly move the demagnetiser back and forth over the tape heads without actually touching them.
Slowly pull the demagnetiser away from the tape heads and unplug, or switch off, when finished.
Some decks have two capstans and pinch rollers so make sure you check and clean both sets if necessary.
Do not use the demagnetiser around any other audio equipment. Make sure your cassette deck is switched off before using the demagnetiser.