Microwave will not start; display shows E1 immediately after pressing START.

Safety first: Unplug the microwave before any disassembly. Microwaves contain a high-voltage capacitor that can retain a dangerous charge even when unplugged. Do not touch internal high-voltage components (capacitor, transformer, magnetron). If you are not experienced with appliance repair, contact a qualified technician.

Steps to check door switches and latch:

• 1. Inspect the door: Open and close the door several times. Ensure it closes evenly and the latch hooks fully engage. Look for cracked or bent latch hooks on the door.
• 2. Check for play in the door: With the door closed, gently lift and push down on the door. Excessive play can prevent the interlock switches from actuating. Tighten any loose hinge screws if accessible.
• 3. Access the interlock switches: Remove the outer cabinet (usually screws at the back and sides). Slide the cover back and lift off. The door switches on Tristar microwaves are typically mounted on a plastic interlock bracket near the door latch area.
• 4. Test switches with a multimeter: Label and disconnect the wires from each switch. Set the meter to continuity. With the door closed, the primary and secondary switches should show continuity (closed). With the door open, they should be open. Replace any switch that does not change state correctly.
• 5. Inspect the interlock bracket: If the plastic bracket is cracked or loose, the switches may not align with the latch. Replace the bracket if damaged and ensure it is firmly secured.
• 6. Reassemble and test: Refit the cabinet, plug in the microwave, and test operation. If E1 persists, stop using the unit and consult a professional, as further diagnosis may involve the control board.