I get your point and I do fear the oil pump bolt on mine going.
If i had more time and space and a decent garage and I could empty the oil out of mine without having to pump it out, I'd have a look at mine!
I didn't think it was down to his oil pump bolt, I was just saying that the vacuum pump needs oil or oil pressure.
We all know his is still fine cos he was able to drive for 40 miles.