As the title suggests, there's a broader question with a narrower application.
What should I do when I want parts for older trains which seem hard to source, including from such mainstays as Peters? Just wait and see? (I say older; I have a modern J83 which I need a plastic chassis frame for, but which is very hard to find.)
The specific case I'm interested in the the 1980s King-class (King Henry VIII). The front bogie's front axle has a worn-off spike-end, which means it slips half-out on any gradient or unevenness. This is bad enough, as it causes a functional derailment, but what's worse is these front bogies are made from metal so the bogie dropping to the track shorts everything. It's also missing a front buffer - I can source the buffer itself, but not its "sleeve"/cylinder, and that doesn't even have a separate parts number.
So broader question - how to source rare parts? Narrower question - any thoughts on X776/X1013 bogie axles/full bogies, and making/sourcing buffer sleeves? I'm happy to do a bit of modelling for the latter.