Quick fix, sandpaper, rub both parts and glue it back together. Or order new ones from Stein Dinse, TLM. Brake bolt sounds to me, must have been on the loose side. I make a water lock on a hose and stick it down in a jar with old brake fluid and connect it to the bleeder valve. Build up some pressure and open the bleeder valve. Not to hard. I always zip tie the brake handle over night to get all air out.
Cheers Tom.