Not what I would have expected, since I've driven one with no vacuum assist and the pedal was very hard. I'm talking about the hoses that run from the ends of the hard lines to the calipers.

As for your stripped bleeder screw, the quick and dirty fix would be one from a junkyard. Since it fits in your pocket, it just might be a free part if you know what I mean.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

OK, I got it. But if those hoses were damaged, wouldn't they be leaking somewhat with the level in the reservoir going down after a while? Nothing like that as far as the front lines go.. Also, the brakes were functioning perfectly well until there was a failure in the master cylinder, which probably I brought about by pressing the brake pedal all the way down when trying to bleed the system that way (by bleeding air at the nipples with an assistant who was pushing on the brake pedal). The master cylinder being very old, it likely got damaged that way.

It's a bit of a mystery to me why it still behaves this way after replacing the master cylinder and ensuring there actually is a gasket at the vacuum booster seal. I think it unlikely that the new master cylinder be also defective, which could explain what is taking place here, but I doubt it.

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1979 240D, W123, 105K miles, stick, white w/ tan interior.