brakes are mushy but the master cylinder is not leaking; could it be the booster

If you have never flushed the brake system then it most likely is the master cylinder. Might try gravity bleeding the complete brake sytem. Xander59 you can do this yourself. This is not rocket science stuff. Contact me at jmgrhm30@gmail.com for help to walk you through this.

usually the booster will make the pedal hard and you will at times hear a vac sound under the dash on drivers side.sounds like there is possibly air in the system or the master cyl cups are letting fluid by pass.ck all wheels for fluid on the inside of all 4 wheels or on backing plates.if not have it checked by your mech.

gravity bleed or maybe primary seal is leaking and it is going into booster