Russell,
I've acquired and cleaned two of these and, from my experience, they're primarily plated, whereas the "canister" is plated tin. I've found that scrubbing them with a soft stainless steel brush will do a great job of cleaning them up quite nicely. After cleaning, I brushed a thin coating of mineral oil on the threads of the screw shaft to keep it from developing any rust.
I hope that helps.
One other note; I hope that you don't find out the hard way about the proper orientation for inserting the lower perforated plate, the strainer plate. The cast-in ridges face down, otherwise the plate can be easily broken if pressure is applied. :'(