You've described a classic, intermittent electrical gremlin! Here's a breakdown of possible causes and how to approach troubleshooting, given the information you've provided

Possible Causes:
LED Bulb Issue (Less Likely but Possible)

While unlikely all six failed at the same time and in the same way, LEDs can sometimes behave erratically as they age or fail. A single bulb could potentially affect the behavior of the others in the fixture, especially if there's some kind of shared circuitry within the chandelier.

Switch Problem (Most Likely)



Arcing

A failing switch (especially a backwired one) can develop internal arcing. This arcing creates a poor connection initially, causing reduced voltage (hence the dim light). As the arc settles in, the connection improves, and the voltage increases to full. The intermittent nature and the fact that you "teased" the switch suggest this.

Loose Connection at the Switch

Even without arcing, a loose wire connection (especially in a backwired switch) can create resistance, leading to the same dimming/brightening effect. Temperature changes or slight vibrations can affect the tightness of these connections.

3-Way Switch Compatibility

While 3-way switches are supposed to be interchangeable (functionally), it's possible you have a slightly mismatched pair or a situation where the wiring wasn't quite right in the first place.

Wiring Connection Issue



Loose Wire Nut

A loose wire nut connection (at the fixture, in a junction box somewhere else on the circuit, or even at the panel) can cause similar symptoms. The initial poor connection causes dimming; as the wires heat up and make better contact, the light brightens.

Backwired Connections

Backwired connections are notorious for loosening over time due to the pressure plate design.

Shared Neutral/Multi-Wire Branch Circuit Issues

If you're in an older home, there could be some weird wiring configurations (like shared neutrals) that could be contributing to the problem, especially if other appliances are drawing power on the same circuit. These can be tricky to diagnose.

Overloaded Circuit (Possible, Given the 20A Circuit)

You mentioned the dining room lighting is on the same 20A small appliance circuit. If something was drawing a significant amount of power on that circuit at the same time (e.g., a toaster, microwave, electric kettle), it could have caused a voltage drop to the lights, making them appear dim initially. As the other appliance cycle on and off, the voltage would normalize, and the lights would brighten.

Fixture Internal Wiring

Internal to the chandelier, there could be a loose connection or even a fault in the wiring within the fixture itself.

Troubleshooting Steps (in order of likelihood and ease)


Replace the Switches

This is your most promising first step, especially since you're already planning to do it. Replace BOTH 3-way switches involved with the dining room light with high quality, pigtailed switches. Do not backwire! Use good quality wire nuts and ensure they are screwed on tight and make a good connection.2.

Inspect/Replace the Bulbs

Even though it seems unlikely, swap out all six LED bulbs with brand new ones (of a known reliable brand). This eliminates a potential variable.3.

Check Fixture Wiring

With the power off, carefully inspect the wiring inside the chandelier. Look for loose connections, frayed wires, or signs of heat damage. Tighten any loose screw terminals and ensure all wires are properly connected.4.

Trace the Circuit (if possible)

Try to map out exactly what else is on that 20A small appliance circuit. Unplug everything you can, then try turning on the lights again. If the problem is gone, systematically plug things back in one by one to see if you can identify a culprit appliance.5.

Inspect Other Receptacles on the Circuit

Go to each receptacle on the circuit and remove the plate to inspect. If you find backwired connections, pig-tail them. Make sure the screws are tight.6.

Check the Panel (Qualified Electrician Recommended)

If you're comfortable and knowledgeable, you can check the breaker for that circuit in your electrical panel. Make sure the wire connected to the breaker is securely fastened. Look for any signs of overheating or damage to the breaker itself. If you are not comfortable working inside an electrical panel, DO NOT DO THIS. Call a qualified electrician.7.

Consider Calling an Electrician

If you've exhausted all the above steps and the problem persists (or if you're uncomfortable doing any of the electrical work yourself), it's time to call a qualified electrician. They have the tools and expertise to diagnose more complex wiring issues and ensure your electrical system is safe.

Important Safety Notes



Turn Off the Power

Always turn off the power at the breaker before working on any electrical wiring.

Use a Voltage Tester

Use a non-contact voltage tester to verify that the power is off before touching any wires.

Follow Code

Make sure all your wiring conforms to local electrical codes.*

When in Doubt, Call a Pro: If you're unsure about anything, it's always best to err on the side of caution and call a qualified electrician. Electrical work can be dangerous, and improper wiring can lead to fires or electrocution.Good luck! Let me know if you find anything interesting! Flag for review