Replacing the brake fluid is not required maintenance on our Dodges, but it should be, just like oil changes. BMW (motorcycles) requires a brake fluid flush and refill every year, at least on my bike.
As you know, brake fluid absorbs moisture from the air. This is the reason for the odd-looking rubber cap seal. As the fluid is used, the rubber membrane will collapse into the master cylinder, thereby keeping air away from the fluid.
This water in the brake fluid will corrode the inside of your brake system in the same manner as it does elsewhere on unprotected steel and iron. The rust then prevents parts from sliding properly, as demonstrated here.
The only cure I know is to dismantle the brake and clean off all the rough surfaces. You may have to replace a caliper or piston. Then be sure you change your brake fluid every so often.
This job is not necessarily a shop job, but you should have a brake hone, and possibly a couple of other special tools, depending on your system. It’s been quite a while since I’ve done my own brakes, so I forget which tools you will need.
My own philosophy about these special tools that I need for jobs like this is that for the price of paying a shop to do the job, I can buy the tools required. Then the next time, I’ll already have the tools.
When you reassemble everything, be sure to grease any external sliding parts with a brake grease, as mentioned above. Don’t use so much that excess will come off onto the friction surfaces.
When I did my brakes, I got pads from TDR member Sam Peterson, who runs Rapid Brake in Washington (state). His number is (360)357-4958. He’s open Monday to Friday 8:30 a. m. to 5:30 p. m. , pacific time.
Good luck,
Loren