May be YSM
Take a look at the locking nut on the wheel.If it has a "Y" you have the discontinued Yacht Specialty System also known as the Merryman.The compass comes off with a few screws. Next a ring with four screws. Now the fun part. 4 more screws for the next ring which you will not get out, but will have to drill and tap. If you get this apart let me know, as I could not.You may try all kinds of solvents and also heat. Stainless screws in Alumininum. When you get here, you should be able to fix it. If you do not have a wheel brake, put one on now as you will have every thing taken apart that you need to take apart. Wheel brake available from this site in the store section.Good luck.Ian