The bush on the rod shaft is free to turn on the C5. Bush, being the bit that rubber gaitor goes over.
I have peeled all that back, covered vulnerable areas with heat resistant putty and had it all glowing red hot. I have used all the punches in all of those thread pics as well

Like you Chris, I cannot centre or see the definition of the pin no more. I will continue to grind it with a stone and lapping paste, through the outside hole in cast iron swinging arm. I have enlarged that hole slightly to try and see the definition of pin. If I can find that, then more heat. When I am sure that my punch can get centre on it, then I can knock on it heavily. A little oil, then chalk might define the outline of the 3mm pin.
I am sure it is flush with rod on the other side, as I drove it through quite a bit from there and got it moving.
I will try all that and see if I can get a nice new pin in there. If it fails then I will leave. If I ever need to renew the unit or gaitor,then I will try the Plasma Cutter in that bigger hole

Any damage then, and I will have a new unit on standby. Any enlarging of the split pin hole on cast metal swinging arm, I can plug weld and drill neat.