Do you not just plug in the laptop now to check compression? I know modern jd’s are like now. Whatever it is, it is going to need stripping down to investigate. Could it have dropped a valve, blowing pressure back past the rings?
The metal will only have come form the lift pump in the bottom of the tank. It is common for these to ware out/fail. The last one I changed on a Audi was only about £150. I would find a reliable independent garage and ask them to do the work
Think the best air con I ever had the pleasure of was a old 8770 (W reg), New Holland’s of that vintage had very good air con. Even a Ts115 I drove around the time had top notch air con. then I got on a Tsa and it all went down hill, was torture turning the same 100a of hay every day for a week :(
It is easy enough to fabricate a perch and to fit a fastener to the call bird compartment.
As said above, these traps are deadly with crows And magpies. My only advise would be to get the larger (higher) trap than the one in the link. It is more expensive but has more space for carrion crows