Watch it!

I broke the pin that holds the needle on my tachometer doing this. They have to come out straigh up, with no sideway motions to loosen them. If you are determined to do it maybe use a noseplyer and have the pine sit in the middle and just pull by the very tip of the plier and from the handle evenly.

Before you do anything you might want to take pics of how the needle sit on their of possition, at their one position, and at 1000rpm, at 20 or 10mph. This will help you to verify if they are working fine onece you put them back together.

or you can take it to a local speedo shop and see if they can do something for you

Good luck