| You can measure the out put with a multimeter. there are 3 wires feeding into it. Live, Grd and signal.
With the ignition on, and at idle you should see about 350mV from the signal wire. At full throttle you should see around 4.8V.
What you probably need to do is set it. That's a little more involved but you need to back off the throttle stop, and making sure the front throttle is closed fully you should have 150mV +/- 5mV. You can adjust this reading by adjusting the TPS on it's lock screws.
TBH, if it is out you really need to get it set up from scratch, get the throttles balanced then set the idle CO.
Adjusting the TPS in isolation will alter idle CO............... | 
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