[KenWittlief]

test them with a known good 5VDC supply, and with a voltmeter on the output. Make sure the voltmeter is on DC (some default to DC or AC when your turn them on).

the output should be on or off when the shaft is not rotating, and you should be able to slowly rotate it and see the outputs change. If your meter has a frequency function you should be able to see the freq change as you rotate the shaft.

A scope would be excellent for this.