Myres 3pt sprayer

I've got a older Myres 3pt sprayer, it is a older 100gallon tank that has a cast iron pump housing.

 

It works great, the trouble I'm having is the screens in the nozzles need cleaning after every tank full, their is small rust flakes in the system, I think it's light rust in everything from the pump housing to the boom's, they are metal also..

 

Question...  is their anything I could circulate through it that will dissolve the rust and not hurt any rubber seals that may be inside, I would like to clean the internals to help keep the rust out and help keep it in good shape, I understand they don't make these any more and I would like to keep it working for years to come...  

 

Thanks, Chris

Myres 3pt sprayer