Relating to the car in my picture. Brakes generally work well enough, but driving in the rain yesterday I found I was unable to lock up the wheels when I tried.

There were also times on track when my brake pedal goes to the floor but not locking-up or activating the abs. It wasn't that much of a problem as I was still out-braking other cars.

I guess it could be air in the system but it doesn't seem to get worse when hot. I bled them myself when changing calipers etc but I have since read that you shouldn't push the pedal past its normal travel when you bleed them as it can damage the seals in the master cylinder - wondering if this is what I've done.

If so, is it an easy swap?> - Disconnect reservoir and then unbolt it from the servo? or is there more to it?

Thanks in advance