My downlights (2x50 watts) controlled by a dimmer switch (Home Automation 50-400VA) have decided to dim by themselves and cannot be brightened at all. I have heard it said that the transformer either works or not (i.e. goes open circuit) and so I am wondering what the fault might be. I have tried replacing the bulbs but no difference. I can't easily get at the transformer so can't say what make/type it is. Help would be appreciated.