Tynecastle,
You're right about inputs being critical. I had a peek at the AB139 MGB used for the 30min certification. It doesn't look too bad, except for the burnt brown paint on the inputs!! I must say though, the input gears were in remarkably good condition considering what they had been through, and considering that the inputs rotate at 21000RPM.
It would be surprising if the Vespels were the main problem here. They have been in use for decades with no problems, as long as they are maintained properly. for the 412, that meant inspect and lube every 300 hours if I remember correctly. But of all the 412 Vespels I've inspected, I've never seen a bad one, just lube it up and put it back. Talking to another engineer, he is of the same opinion, unlikey that the Vespel is the main problem, expecially with only a small number of hours on it (what is the total time on this particular machine??).
Noooby