I built a wheel for my girlfriend's town bike around an XL-FDD. Four years in (with daily use), the braking power is fading - it takes more and more lever pressure for the same stopping force. Yet the wear adjustment is less than half-travel.

I wonder if some grease leaked into the brake lining? Feels like disc brakes that have got oil-fouled pads.

Or is this normal?

Other than that, the dynamo half has been flawless.