Sounds like a similar situation that I experienced except in my case the damage was self induced. First time to step the mast, separated the mast base from the mast with the mast step acting like a can opener, like most lessons this is one I'm not likely to forget since I learned it the hard way. Fortunately the mast base wasn't damaged but the rivits did pull thru the bottom of the mast, according to experienced hobie sailors of the day the fix was as easy as drilling new holes in undamaged locations and reviting together. This occurred back in 2003 and so far so good......Good luck with your fix and make sure to watch your mast stepping technique assuring the ball of the mast base is aligned to the mast step before that last final push-up.