I have two dimmer switches that have started malfunctioning. They are in the same box with two other standard switches. Each controls a set of three small flood lights. There is no other way to control these floods except with the dimmer switch. They were working fine last week. Now, when I slide the dimmer, it sometimes works and sometimes doesn't. I know it isn't a circuit breaker problem since the other switches are on it as well and they work. These were installed about 6 years ago. I will need to call an electrician to fix this but would like to have an idea, if possible, of what the problem could be.
Sounds like a simple case of a bad switch.
Note: a squirt of WD-40 into the right place in the sliding mechanism can help, or even fix the problem at least temporarily by lubricating the internal sliding electrical contacts. But getting the location right requires experience, and if you have to bring out an electrician anyway, they'll prefer to replace.
Do this with the power off by the way. And it's far better to take it apart and lubricate, compared to the squirt and hope method.
Consider upgrading to a dimmer model with a remote control, CFL compatibility, or other features.
Your dimmer was probably damaged by excessive heat and maybe more load than it is rated for. Solution:replace bad dimmer with one that is rated at or above the amount of watts you are controlling with it if one dimmer is a 3 way you may be able to put that one on the other end and a regular 3 way switch at that box. Otherwise you may be able to change your lamps to dimmable led s that will reduce the load and also the heat. But still replace the dimmer they are not repairable.