97 blazer antenna replacement

How do you remove and replace the stock antenna? I think I have a broken shield at hte base of the antenna. The two sheet metal screws hold the base mount in the fender near the ac/heater box. how do you get it out?

thanks,

bernie

I figured out a temp fix, and it reduced the noise dramatically, but it isn't eliminated. I disconnected the motorola coax connector and slipped a piece of braid over the cable as far as I could under the fender. I then clamped it to the cable with some large alligator clamps so it contacted the metal frame. the other end I clamped to the outside of the motorola connector with alligator clips and then jumped it to the chassis for a ground. At this time I will await a more permanent fix.

bernie