You can get a 6v red led that will fit the socket from these guys. Then it'll be red no matter what the condition of the lens is. The LED end of the bulb may be too long to fit (mine was). I just ground the end down (the LED is set in resin to form the "bulb") until it fits. Be careful not to go too deep. I destroyed my first bulb by grinding too deep & getting into the LED. They are fairly cheap so buy two in case you do ruin one of them. If you don't you'll have a spare.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.