I got my OZ gauges about a year ago and noticed all my gauge needles are off. The tach is off maybe 250-400 rpms, speedo is off 7 mph, temp gauge maybe 1/4 in, and gas light turns on right at 1/4 tank. How would I fix them so they all sit right and give me the correct readings?

 

I got the idea to pull the temp gauge off, and try setting it when the car is fully heated up, but I have big fingers and cant seem to quite pull it off of there. Whats a good way to get the gas and temp needles off?