The belts can be found at this link HERE
Here are the steps to disassembly and install the new belt kit:
1) Unplug the power cable for the Sony 400 CD for safety.
2) Lets start, the top metal cover is taken off by removing 2 screws on each side, 2 on the top, and 3 on the rear.
3) Once the 9 top cover screws are removed the trick to removing the top panel is holding each side, pinching them up and out, then lifting up on the cover.
4) Worn belts will be visible at the rear (back left looking at unit from the front). The two belts are not easily serviced at this point, however it is much easier to remove the back pieces to have easy access to installing new belts.
5) To remove the back pieces start by removing the 9 screws holding the black plastic humped assembly at rear, then it can be pulled to remove. Next, remove another 9 screws holding the flat black panel. Once the screws have been removed there is a plug at the left rear that can be un clipped for the power cable to allow the panel to be separated from the rear.
6) To remove the rear back panel let the unit hang over the edge of a table by about an inch and pull down lightly on the panel. The panel will pop loose allowing you to move it a couple inches out of the way to access the old belts and pulleys new belts will be install on.
7) Remove the old belts and any black rubber residue traces from the pulleys.
8) Install the two new belts. Make sure the belts are in the pulley grooves securely by spinning the pulleys lightly several revolutions.
1) Hold the silver "T" shaped piece at the top-left rear and push it through the black flat panel. Next, attach the power cable plug clip that was removed.
2) Align the black panel with the 9 screw holes and re-install the screws.
3) Align the black plastic humped piece with 9 screw holes and re-install the screws.
4) Install the top panel.
5) Power on the unit and enjoy hundreds of hours of new CD play with your new belt kit installed!
Hopefully, you have successfully been able to fix your Sony high capacity mega disc changer. If you are still having trouble you can send it in to us for repair. We have tons of parts for many different Sony models and can get the job done perfectly. This repair tutorial applies to many different models. Including, but not limited to model numbers CDP-CX400, CDP-CX450, CDP-CX455, CDP-CX355, CDP-CX300, CDP-M333ES, CDP-CX335, AND MORE. Also, keep in mind, we have inventory of refurbished CD players and Vintage electronics that are just waiting for you to buy. Thanks for reading this how to on Fixing and Repairing Your Sony 300 or 400 Disc CD Player.