That cocked adjuster cap on the wheel cylinder is a good place to start looking for a leak. Chances are there's a corroded or damaged piston behind it. Finding new Huck brake wheel cylinders can be a challenge- - - -they're definitely a lot less common than ones for the newer Bendix-style brakes.

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!