Clive, I used a impack screw driver like steve did. I was able to get the srews out of two out of the four holes that was. On the other two I cut the top of the bolt out using a hack saw blade. Than I use a penatrating oil and a pair of vise grips to remove the other two after I removed the mast butt fitting. Make sure you work the bolt back and forth as you try to loosen them and tap on the top of the screw driver once a a will to help free them up. Before you work out the bolts try to clean out the slotts in the mast butt fitting and use a lot on penatrating oil. I loosen you boltd every year now one at a time and coat them with anti seize. I now use 1/4 20 hex head bolts with fedder washer to hold the fittting in place.
