6 lights? What wattage/type? The dimmer may have been overloaded, explaining why one now doesn't dim, and the other packed up.
The switch for the blown lights has never (since I have had the house anyway) worked as a dimmer, it just turns, clicks and comes on. These lights are near the worktops, oven etc so I assumed there was no need for a dimmer there but the previous owners wanted macthing switches.
The other lights in the kitchen do have a working dimmer switch, they are at the other end of the kitchen where there is dining table etc so I can understand why the previous owners would want a dimmer there.
the lights are 50w halogen bulbs and there are only 4, not six as I previously said, on each switch.