The amber light doesn't come into play for the first 35 seconds the machine is on. After 35 seconds, it switches into the second cycle when the macerator is running and the electrodes are activated. This is when the heavy load is applied to the system. So a green light for the first 30 seconds or so, is normal. Then when the electrodes are activated and the heavy current draw takes place, is when you'll see the lights sometimes change color. Alternate flashing between green and amber indicates that the salt percentage inside the treatment unit is marginal. When it stays on a steady slow-blinking blinking amber (once per second), the salt is too low. And when it goes to a slow blinking red, then shuts down after 5 seconds, means that there isn't nearly enough salt inside, or that the electrodes are dirty - or have gone bad. The slow blinking red light will stay on after the machine shuts down, telling you that it never completed the last cycle, and that something is wrong. Pressing the "R" button will reset the system, but it will probably short-cycle again.
A steady red light, not blinking, indicates a blown fuse. This is rare. The most common situation is a slow blinking amber (or red) light.