There are sixteen, socketed Optoisolators on the LE. They are between the small green LED and the monster heat sink. Their purpose is to electrically isolate the 110vac or 220vac from the control chips. Inside is a very small LED and an equally small light sensor. So, the signal to turn on the TRIAC (they are the device screwed to the heat sink) goes through them.
I suspect that you have two (#12 and #14) that are too sensitive and triggering when they don't need to. If it is the Optoisolator's problem, it will move with them. If not, it won't move.
It is also VERY possible that moving them will make the problem go away completely. You may also find that one of the Optoisolator has a leg that is bent and not actually inserted into the socket, making partial contact instead of solid contact.
While you SHOULD use a chip puller, I usually just use a very small pocketknife blade and gently pry each end, alternately, until the chip pops out of the socket.
Do I need to tell you to unplug the board first?