Here's another thread that has the wiring diagram on it from a few years back for reference, its for a WC-60, but they are all the samehttp://soda-machines.com/discussions/index.php/topic,1562.0.html
The only place that I can think of right now that would cause an issue is if there is something wrong with the Empty Switch normally closed (N.C.) circuit. Your 'Make another selection' light coming on shows that the normally open (N.O.) is working fine.
The switch is inside the main cabinet, in the center of just below where all the bottle racks are. There should be two flat head screws you can loosen and pull the front metal cover off the whole assembly. You will be able to access the switch and test the voltages right there to ensure that everything is working.