i recently bought a new brake bleeding kit containing a brass metal hand pump. i have fitted my couplers and hoses etc.. all seem to fine. i can't get any suction though. i can place the coupler end on my skin and give a few pumps and receive and maintain a vaccum, but when i connect to the cylander, i loose vaccum. the female coupler is new and made of metal. is it possible the cylinder could be wrecked? is there any way of testing what exactly is defective before i purchase any more parts?