Fisherman's Group Fishermans Boat Group-Service (Miami,FL)
They work on my Yamaha and they also work on Mercury.
If you don't have transportation, there is a good mechanic over by the Marine Stadium that you could get to by boat. I'm not sure if he works on Mercs but I can check tomorrow.
I second Capt Jerry, it sounds like you spun the hub on the prop. You just need to buy a new prop or get the old one re-hubed.
I'm in Miami and I work in the marine industry. If I can help you in any way, just send me an email at hopcarmarine at yahoo dot com.