1995 GL1500 SE w/Lehman straight axle, drum brake conversion, 98,XXX miles. While on a trip approximately 2,500 miles after installing speed bleeders & replacing the brake & clutch fluid, lost all braking in the rear circuit. Parked after a day of riding with normal braking, went out next morning to go some more & no rear brakes. No sign of leaks where parked. Reservoir was empty. Filled reservoir, bled brakes & all was normal. When I got home (about 2,500 miles later) I removed the rear drums & inspected all braking components, including the front left brake. NO evidence of ANY leakage anywhere. NONE. Inside of drums was very dusty, shoes are about 50% worn, but completely DRY. Any suggestions as to where the brake fluid went? I am stumped. TIA, Stan