No metal plunger shaft is a crucial design flaw. MY original worked for a couple of decades. now plastic takes all the human torque with each stroke = after a few trips it's not smooth. Also the flame adjustment is gone unless you have a simmerlite.What a great way to de-volve an otherwise fine product by making it cheaper and plasticky. Lame decision IMO.MSR made better products in the 80's when users were still involved in the design.