The present invention provides an improved write circuit and method for writing a programmable conductor random access memory cell. At least one cavity insert is removably mounted within a cavity plate, the at least one cavity insert defining a mold cavity, and a first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity. The flexible portion enables the needle to bend to a penetrating angle relative to the distal end of the elongated tubular member and penetrate a body tissue without kinking.