I ended up going with the hammer. Made some marks on the wrench but I DID manage to get the fixed cup off. All is well. I can not believe how much force that took. I work on tandems all the time and rarely have to work that hard to get something loose. On the other hand, this fixed cup was in place for 25 years and had 25000 miles on it.

I will have to investigate adding a breaker bar to the tool set. The hammer just seemed wrong.

Thanks