Hydraulic attachments

On a job last week switching between breaker and bucket . Cat 304 . Every time we went to put the breaker on we had to loosen the fittings on the machine to hook it up . Flat face couplers that looked to be in good shape . I shut machine down , key back on and wiggle all the buttons . Pressure was always on the machine side . How do you bleed the system ? Thanks , Kevin .

Hydraulic attachments