Do you have access to a schematic?
Otherwise, there are a lot of variables. Is the machine looking for a specific color?...specific intensity? Is that a cylindrical LED, or does it have a cover/lens on it? What voltage is supplied to the LED?
You may want to check through a catalog from a supplier like
www.mouser.com
Cylindrical LEDs are at the bottom of this pdf page:
http://www.mouser.com/catalog/631/115.pdf