My agitator bolt will not come out

I am trying to replace the agitator dogs on the upper assembly of my Kenmore 600 washing machine agitator. It was easy to access the bolt, but when taking it out, the wrench turns and turns forever. The lower part is not moving and I can hold it still but I get the same results. Anyone encountered this before?

DID YOU FIGURE OUT HOW TO REMOVE THE BOLT? I AM HAVING SAME PROBLEM WITH MY ARMANA WASHER. I DONT KNOW WHAT TO DO.

Hello.
What is the complete model number of your washer?