Marklin 4097/6 on air with working dynamo

The dynamo on this Marklin 4097/6 did not seem to produce any voltage. I could tell the magnets still had 'power' so something else was up.
I was able to see that the contact to the armature was not contacting the way it should. I could see it was an easy adjustment so I gave it a shot. I hooked up the multimeter to the dynamo posts, turned on the air, and it took off and produced up to almost 4 volts AC. I didn't push it to maximize the voltage, but I will. Maybe I can get over 4 volts!