Brakes and a leak on my Ranger

My ‘92 Ranger needs new brakes and has a leak somewhere as well. According to my dad, this was a recurring problem with the brakes when my grandmother drove it (pumped the brakes like crazy). I’ve replaced pads and rotors many times on several vehicles, but not sure where to start finding this leak. Any tips?

Does it require topping off the fluid?
If so, the leak is external and should findable by looking for the fluid. If you’re not already aware, brake fluid is great for removing paint, so be mindful when handling.
The usual suspects on this system, in descending order of likelihood in my opinion: wheel cylinders (bad leaks will show up in wetness on the backer plate, observable from behind the wheel, pulling the wheels and drum may be necessary for smaller leaks, and really minuscule seepage will be spotted by squeezing or peeling back the dust boot on the cylinders), proportioning valve, lines/hoses, all observable by eye, typically. The master cylinder, and calipers are unlikely, but possible. Basically check for seepage/ squeeze/peel back the dust boots (have to get under the dash for the m/c).

If they “leak down” but don’t require fluid addition, check adjustment on rear drums, for good sliding pins on the front calipers, suspect the m/c leaking internally if those check out…

If you do not have any visible leaks, the master cylinder could have issues with the seals. In case of the drums, there should be a residual check valve that keeps the fluid from the drums bleeding back out of the drum pistons. Your drum springs could be over powering that valve allowing the fluid to return back to the main lines.