My well pressure is fine, but the pressure switch seems to be getting noisier, it was replaced about 18 months ago

Describe the noise. Loud clicking? Chatter? What? Back to you, Tom

More of a humming noise

The only things moving are the contacts. What's left are the windings. Does it hum all the time? Back to you, Tom

he only things moving are the contacts. What's left are the windings. Does it hum all the time? Back to you, Tom

Only when we're runnibg water

Then it's in the windings. I see no harm in that as long as the windings aren't heating up but if the hum bothers you simply replace the control box. Good luck, Tom