An improved pump, reservoir and reservoir piston are provided for controlleddelivery of fluids. A motor is operablycoupled to a drive member, such as a drive screw, which is adapted to advancea plunger slide in response to operation of the motor.The plunger slide is removably coupled to the piston. A method, system, and anarticle of manufacture for automatically detecting anocclusion in a medication infusion pump is provided. The electrical current toan infusion pump is measured. Based on measurementsof one or more variables； the infusion pump detects whether there-is anocclusion in the system. The methods of detecting occlusionsmay be dynamic.
