We revived the damaged Z9 simply by carefully extracting the loose, stuck tile of the shutter curtain. The remaining tiles seem OK. By setting the curtain option to 'OFF', the cameras happily soldiers on as before. I just have to be more careful as the sensor surface now is entirely unprotected during lens swaps.
During the stuck curtain incident, I got some heavy crud on the sensor, but nothing worse than can be removed by deep cleaning (hopefully). Anyway I could record the morning pea-soup fog we experience at present. Setting the fast Viltrox lens to near wide open, most of the dirt on the sensor got blasted to oblivion by unsharpness alone. So task myself with a deep-rinse of the Z9 later today.