Evapo-Rust is big with the Classic & Vintage bicycle crowd for cleaning without damaging the underlying surface.  For small diameter brass tubing I'd look at a hobby shop. They probably offer several sizes but perhaps not in the correct wall thickness.
Stephen  

    On Friday, June 30, 2017 11:37 PM, Neil N <musomuso@GMAIL.COM> wrote:
 

 And here I thought everyone had an ultrasonic cleaner ..... and 3D printer.  ;)

I bet that Harbour Fright stuff will do the trick.

Neil.

On 6/30/17, David McNeely <davmcneely40@gmail.com> wrote:
> Well, no access to an ultrasonic cleaner.

> Well, this stuff is in the bath so to speak right now.  We'll see what
> happens.  I may be contacting those shops that change out the refrigerators
> in Seattle.

--
Neil n

Blog: Vanagons, Westfalia, general <http://tubaneil.blogspot.ca>

1988 Westy Images <https://picasaweb.google.com/musomuso/New1988Westy>

1981 Westfalia "Jaco" Images, technical <http://tubaneil.googlepages.com/>

Vanagon-Bus VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>