Rebuilding the First & Second Stage Piston on a YH

Is there a site that sell a "Rebuilding Kit" to overhaul a Yong Heng First & Second Stage?

Does it make a difference if it has some of the the bells and whistles when it comes to choosing the kit?

I took it apart and see it's comprised of mostly orings, head gaskets that probably should be replaced. Are their other item that should be replaced?

Many thanks!
 
My YH has had about 6 hours of run time and the only thing I have replaced is the check valve O ring at the high-pressure outlet. I have replaced the low-pressure piston with the new version which has got a thicker top hence stronger but that's just a precaution, the original piston is still in good shape. 

The only essential thing I have done is to clean the reed valve at the top of the high-pressure cylinder. Greasy stuff has accumulated here preventing the reed valve to close completely. Note that there are two reed valve blades here, one on each side of the center block of the cylinder head. The picture below shows the center block removed from the cylinder head and one of the reed valve blades. 

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