I have a Kona dew deluxe with screeching brakes. Pads are pretty good but bike hasn't been ridden much over the past 6+ years. Had the brakes checked over and was told they might be leaking fluid. Lever pressure is good though. Wondering if pad deteriorated from not being used?
I cleaned the rotors with soapy water but no improvement. I am wondering since they want to replace the brake unit to fix it.
As you say there's nothing wrong with the lever feel, I'd normally say the first thing is to replace the pads (or even just check for embedded grit and sand them to a new surface) the second to recentre the caliper, and the third to sand the rotor.
But a couple of other things are worth checking. The first is that you don't have a stuck piston - if only one is moving properly it can cause a squeal. The second is, as you've mentioned, to check for leaks. I've had leaky disc brakes, and apart from the squeal, the lack of braking power was really obvious. They were as bad as old cantilevers on chromed steel rims in the wet, only less consistent. A steady descent burnt off the oil, leading to better and quieter baking, but that's not a good way to test if it's both brakes.
If you're sure they're leaking, it may be possible and worthwhile to fix that specific brake, or it may not. I replaced mine, but they had other issues as well.
