The vending motor assembly on this machine is very simular to a Westinghouse select-a-matic, if the motor & vending link/arm keeps cycling, you should check the big vending switch thats attached to the motor arm assembly, this switch is what controls the vending cycle when a selection is made the motor starts to turn, this switch then gets closed by the cam or arm to keep the motor running after the selction switch is released to complete the vending cycle, once the cam or arm gets back to its "home" or parking postion, it's supposed to open up the circut that supplys voltage to the vending motor & stop it from rotating again until another selection is made. so, if the motor is running constantly, you can be sure that this little bugger of a switch has a lot to do with it. this switch is used in the "normally open" postion, that is to say, it's "off" with the vending motor in the parked position.
make sure that it has all of it's wires attached to it , normally it has a three wires going to it, but some machines only use two. also check to be sure that it's mounting screws that hold it against the motor assy. are snug, & that the long lever that contacts the motors cam or arm is correctly postioned & not bent or missing BE VERY CAREFULL when adjusting this switch! it will trigger the motor & you might get a nasty surprise when it rotates without warning & snags your fingers!!! adjust it with the power OFF, the same goes for the Westinghouse select-a-matic machines too. unless you like the nick-name "stubby"
you can disconect the compressor by turning the thermostat to "off" when adjusting this switch, so it doesn't have a fit when you keep unpluging the machine to test the vending cycle.