Hope this doesn't happen to us! So have you tested to make sure they are getting power (12v)? What I really dig about them is that you can trouble shoot them whether they are plugged into the RC or not, all you need is the 12 volts. The red LED on the back of the Receiver lights up when active, but I'm guessing you already know all this. Random thought, isn't there some way to actually 'see' the IR light? Like some special goggles or something? Another thing to check (after you verify your sensors actually have power): There are sensitivity pots that can be fiddled with depending on the application. If you are using a "broken beam" type of scenario, the sensitivity can be dialed down, but if you are using reflected IR (like we are) then you have to turn it up. Establish the conditions that should turn your sensors on, then turn the pots until the red light appears.
If none of that works, then I guess you have to get new ones (you would have to get them from the supplier). Isn't it strange how you can load a perfectly good robot in a crate then two weeks later open it up and pull out a broken one? Seems to happen over and over again
