Ahhh... well today I figured I could see the master cylinder from in the frunk

. Doh... spent part of a day wasted underneath the car with brake fluid and all kinds of debris falling into my eyes and all over me (whilst lying uncomfortably on the floor!).
It seems both rubber seals on top (the two parts for front and rear brake fluid circuit top up) may be perished as they are leaking (the one nearest to the rear of the car is worse) from around the plastic push in pipe connectors... are new seals available? Perhaps I could try some PTFE tape or similar (if it doesn't perish with brake fluid!) around the plastic push in part?