If it works but it's just real slow. STOP PUTTING THEM UP/DOWN UNTIL YOU FIX IT! Using them this way will destroy the regulator in the door.

Now, the fix is real simple. If they work, but just slow, go get a can of spray silicone and lube up the tracks. This is a common issue with the X's and once in a while a little silicone spray works wonders on the windows.

On the other hand, if they don't work at all, then I'd suspect an electical problem. But if they just work slow, all the electrical is most likely OK.

-G