Brake Fade Issues

This is all excellent advice. I commend all of you.
I didnt feel it was my place to mention the fact that op was new to brake work and should seek help when repairing them. But mopar leo is dead on the money.

Being in the trade i can say that your brake system is one of the easiest to service,and with the assistance of someone knowledgeable it will all become obvious as you work on it.

New master cylinder all the way.
But pull the old one apart and look at it, if anything just to understand and satisfy your curiosity.
I had a brake service manual from the 40’s,it was thorough in the service and overhaul of all the brake components. I may check if i still have it.

When i was 15,in auto shop class there was an awesome textbook,
Would come in handy for situations like this.all theory and operation.