Don't remember having that problem when I did mine. If you raise the suspension does it give you enough clearance? Assuming it's part of the body that's in the way.
If the leak is less than the vacuum pump provides then I'd say the above could happen.
I've never changed one yet so no idea how difficult it is.
You were asked if you had access to a vacuum pump to connect to the servo?
Easier if you stick to one thread but from the below description of the servo it could be a leaking diaphragm.
Brake Servo
The brake servo assembly provides power assistance to reduce the pedal load when braking. The assembly is
attached to the front of the pedal box and comprises a circular...
I got a 10 ton bottle jack where the top section has a screw thread to make it taller. It just about gave enough lift to get the wheel off, it wasn't until I had a flat that I found out it then wouldn't fit under the jacking point with the threaded bit extended.
Fixed my low screen wash warning.
Fitted new sensor, ignition on, still there.
Drained and cleaned out the washer bottle, refitted, igition on, still there.
Found a broken wire, fixed it, ignition on, gone :) and only took 3 hours.