The best advice for a broken H 260 mast is to replace it. It is an aluminum estrusion and the forces exerted on it are quite a bit. Once broken, the integrity is gone. Suggest getting a new one. I speak from experience as one who was very much involved with this boat from the inception to include mast, as a dealer, as a former claims adjuster/investigator, repairs and so forth. This is one thing I would never repair once the integrity of the extrusion was damaged. I replaced too many from being repaired as well and thank God no one was ever hurt.
I have seen welds break. Also if trying to put a sleeve inside or outside of the masts, then a special sleeve would have to be made to fit that mast extrusion for example Selden Masts. In this case there were never any sleeves made for the h 260 masts as I know that to be a fact. Anything else, the mast will break as I have seen that too.
crazy dave condon