I have an old set of M20s that have been working well until now. Now when I power them on the alert sound stays on continuously. Before it would do the normal test phase beep, then another beep about 30 seconds later. Now it just stays beeping the whole time.
I've checked the heads with a camera as they're doing this and all the LEDs are firing.
I haven't changed anything in my car recently so are there any thoughts on why they're doing this all of a sudden?