You will want to do a little investigating before you place your parts order. Inspect the compressor and see if you can isolate where the leak is coming from. Check the pressure switch base to see if it is cracked were it joins the tank nipple. Inspect the nipple itself for corrosion or a crack. It is possible that the connection between the nipple and the pressure switch or tank could be leaking and will just need to be resealed. If it is a large leak then it is most likely the problem. If the leak is just minor then the problem may be with the pump rather than the small leak.
The most common cause for a compressor to run but not build pressure is a worn out piston and cylinder. If this is the case the cylinder and piston will need to be replaced. The cylinder and piston are sold as an assembly. The assembly is part #882-596 and is available from http://ereplacementparts.com
I hope this helps with your repair!
-Mark
Compressor pressure switch Question by J Cheshire
My Hitachi pancake runs and shuts off correctly, however when it stops the air is released from the pressure switch housing until it falls to around 60psi. It fills again and repeats the process. Is there any hope of repair? This switch is now said to be obsolete.
Thanks, Jack
I did some digging and managed to find a switch that'll work for your compressor. It's part number 882-609 http://www.ereplacementparts.com//hitachi-ec10sbsl-compressor-oil-less-pancake-2hp-cfm-90psi-parts-c-7927_13217_15377.html, and you can find it on figure 129 of this page.
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