If you are US military I would be willing to advise you for free.  Any way to contact you?

Measure the loss first, it may be ok. B1's use positive pressure to keep gunk out of the waveguides (although that only works so so). Call another base, there's bound to be extra.

For a simple physical cleaning, get a long string or monofilament fishing line, use a block or smaller waveguide that fits inside your larger waveguide, attach scotchbrite to the smaller waveguide and pull it back and forth to clean out the waveguide. That still may not work to clean it if plating is corroded away from the inside of the waveguide for low loss. You'll have to measure the loss and hope you don't have very high power going thru it, arcing is fun to watch, but harmful.

Good luck soldier,

kchiggins.

I can be reached at bull.j.oneill@us.army.mil   I thank you for any input you can give me.  I wish it was as simple as contacting another base and getting an extra from them.  LOL, another unit giving up their spare willingly.  That is funny.  I have been using contact cleaner and then using air pressure before and after to blow the waveguides out.  It is doing a pretty good job.