Master cylinder is quite reliable if brake fluid was changed in time. If not then there might be internal corrosion due to humidity in brake fluid. Changing seals is simple enough when you have your cylinder on the bench. Taking it out again and messing with brake bleeding is a much bigger job. I would change the seals as they do wear and at the same time you can inspect internals.
Thanks for all the info. I’ll probably leave my reservoir and MC alone for now, maybe get to them this summer.
Not sure if my low fluid detector is working or not, I will test it once I get the car running. But until I get around to replacing with a Mitsubishi, I know if my brake fluid is low by just pushing the pedal. If it goes all the way down to the floor without any resistance, I’ll know it’s low.