Bad trim sender unit or trim gauge?

[dlogvine]

I just replaced the trim sender and limit units. Adjusted both, limit works fine. The trim gauge is however not working well. When I tried to adjust it it was jumping from full up to full down. On the lake it was moving when I lowered the outdrive, but halfway through it went all the way down, then all the way up. And motion of the arrow on the gauge was not smooth, but very jumpy.
should I try a new trim gauge or could it be a problem with both old and new trim sender unit?
Thank you

 

[alldodge]

Place a voltmeter on the sender terminal of the gauge. Raise/lower the drive to see if your getting a smooth slight change in voltage. If its smooth and gauge jumps, then its the gauge. If its not smooth voltage change then its the sender or its connections

 

[dlogvine]

Place a voltmeter on the sender terminal of the gauge. Raise/lower the drive to see if your getting a smooth slight change in voltage. If its smooth and gauge jumps, then its the gauge. If its not smooth voltage change then its the sender or its connections

Thank you