Cassette gets entangled, and does not play well

Cassette tape machines will occasional require maintenance after a certain period of usage. First open the cassette door and remove the tape and any broken tape remaining inside. Some models allow you to remove the cassette door allowing you to have better access to clean the unit. Next you will need to clean the capstan with alcohol and a Q-tip. The capstan is the metal post which the rubber wheel (pinch roller) pushes against to drive the tape across the tape head. Basically clean all the shiny metal parts including the tape head. Some of the tape residue may be difficult to clean, I use Tricloroetilene which has been regulated by the government, but you may try a product called Goof Off to clean the difficult parts, but it could eat the plastic and rubber parts so be careful. Next use a rubber cleaner on the pinch roller so you do not dry the rubber out, or it will become useless. The other problem is the cassette may be driven by a motor and belts. The belts may need to be replaced and the pulleys cleaned. For this you will need to disassemble the unit to access the belts but the cleaning of the pinch roller and capstan may fix your problem, if not you need to open it up to replace the main belt.