After breaking the edge of the exhaust cover with the wedges (hopefully my parts supplier can source another for me..), I had to dremel out the exhaust cover to expose the bolt that wouldn’t shift. No sign of a stuck impeller vane, but the lack of water flow / pumping was caused by a build up of salt & grit blocking the (narrow) intake channels in two places – a lack of flushing issue. Will take the powerhead to a machine shop to get the broken studs removed, they’re mild steel and don’t want to shift, despite heating cycles and penetrant.
