I'll take photos of my top wishbones and send them in ASAP for looking over....although they are of the earlier manufacture that doesn't seem to have suffered the failure mode. Hopefully you can assess the condition without the need for me to dismantle the car and send the parts.
I am concerned that you believe other non-Marlin parts may have 'had a degree of responsibility for the parts failure'. Can you please be more specific as to the 'non Marlin' parts involved and, importantly, how they may have contributed to the wishbone failure, so that I and others on the forum can satisfy ourselves that our cars are not at risk. Safety is obviously paramount to us all.