Why is my over flow tray always filling up and not the cup

It sounds like you have a problem with your Breville Dual Boiler BES900 - BES900XL. There are a few possible causes for your overflow tray filling up and not the cup, such as:

• A leak in the group head or the steam wand that causes water to drip into the tray. You can check for leaks by inspecting the seals and gaskets of these parts and replacing them if they are worn or damaged¹.
• A clog in the group head or the steam wand that prevents water from flowing properly. You can try to unclog these parts by using a pin or a needle to poke through the holes and remove any debris or scale¹.
• A malfunction in the solenoid valve that controls the water flow to the group head. The solenoid valve is an electronic component that opens and closes to allow water to pass through. If it is faulty, it can either stay open and let water run continuously or stay closed and block water completely².
• A problem with the descaling process that affects the water level sensors in the boilers. The boilers do not have drains, and due to the electrical current carrying capability of descaling solution, the boilers may think they are full when they are not, and can trip the thermal fuse if they heat up while mostly empty³.

To fix your problem, you will need to identify which part of your machine is causing it and replace or repair it accordingly. You can use some tools and methods to help you diagnose and fix your problem, such as:

• A guide on how to descale the BES900/BES900XL Breville Dual Boiler³. This guide will show you how to properly descale your machine and avoid damaging it.
• A guide on how to replace the group head collar insert¹. This guide will show you how to access and replace the part that holds the group head seal in place.
• A guide on how to repair the solenoid valve². This guide will show you how to test and replace the solenoid valve if it is defective.
• A forum where you can ask questions and get answers from other users of Breville Dual Boiler BES900 - BES900XL⁴. This forum will allow you to share your problem and get feedback from people who have experienced similar issues.

I hope this information helps you solve your problem. If you have any questions or issues, please let me know. 😊