Yesterday I noticed what felt like a lowering of the point where the brake pedal took pressure on my '67 250SE. I have been driving a number of different vehicles lately so wasn't sure that it had changed.

However today it definitely was suffering a loss of pedal pressure, and checking the reservoir I found it next to empty on the brake side.



Trying to see where it had been leaking from was hard - there is some oil that leaks slowly from various places so there are numerous 'damp' sections... however I noticed behind the right front wheel a wet looking section at the back of the wheel arch.



The only thing I could see that looked like a leak above this was the rubber seal between the hose attaching the reservoir to the brake servo. It looks pretty dead...



But would this explain a loss of brake pedal pressure? Would it need a leak further down the system for the fluid level in the servo to drop enough so that this leak would cause trouble?