How do I replace the Master brake cylinder?

Hi there,

You should use a brake pipe spanner for the hydraulic lines, as an open ended spanner my tend to round off the nut if it is to tight, just undo the switch wire, undo the hydraulic lines and unbolt the master off the booster, bleed the master on the bench first, re fit and attach hydraulic lines, bleed the full hydraulic system and all should be OK. This guide and video should help you do the job

https://youtu.be/WDxvEQrMkBg

and

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Please run down these guides and report back.