There are 2 transfer switches. The external tank transfer (triangle head, on the left console) and the internal wing tank transfer(slightly further to the left and back. INT WING TRANS). The internal wing tank transfer switch is set to NORM by default which is where it should be(STOP TRANS is where you *don't* want it to be in this case). The external tank transfer will prevent the internal tanks from transferring however, if there is a tank in place and it is in any position other than OFF. While on the ground, you will want to set the switch to OUTBD or CENTER (depending on your choice and tank config). That way it will be ready to transfer when you get off the ground. You will know it is transferring if the green light for that particular tank on the annunciator light panel is off. If it comes on, no worries as it is intermittent in transfer. However, if your internal fuel (outer slider. NOT the counter drums) drops below 8000lbs and the lights don't go off then you can know that tank is empty.