Loud humming

If this is an electric resistance heater then there is no power supply or transformer. I had a baseboard heater that would hum loudly and I found there's a wire that runs along the bottom to connect the far end of the heat element to the electrical wiring at the supply end. This wire becomes magnetized from the current flowing through it and vibrates in the channel it runs through. I was able to open this channel and squirt a bit of silicone caulk in to keep the wire from vibrating and the hum is gone.