[Dukedesmo]

I'm currently restoring an old Land Rover and, as such have experienced pretty much every type of seized bolt available, most of which I have just cut out because there's no real alternative and I'll be replacing them anyway.

But a few, where they are in 'sensitive' areas such as aluminium of gearbox housing etc. have required a little more of a sophisticated approach and I've resorted to drilling or drilling then slitting through the bolt, to welding a nut on to a stud or broken bolt, giving something to grip on but, also getting some serious heat into the thing that can help release it and this seems to (mostly) work reasonably well as the weld won't stick to the ally but will heat it up quickly which can help break the bond.

Not sure exactly how the sie swingarm is? but maybe, access depending, you can weld an allen key (ideally one with a socket attachment on the other end) into the head of the bolt so that you can get some proper leverage on it without rounding the bolt head, the heat may then help release it?