Automatic gear stick on 2002 Oldsmobile Alero

I have a 2002 Alero. The button on my gear stick snapped off and I have it taped in. How would I remove it and place a new one on? I went to a body shop and the mechanic told me I would need a whole new transmission. This I do not believe.

Asked by for the 2002 Oldsmobile Alero
There is a retainer in the front of the shift knob. Remove it using a flat bladed screwdriver and then pull straight up on the shift knob to remove it.