Starts a little slow but does run up to pressure. , but will not restart when the pressure drops to the point where it should s5tart. It just hummmmmmmmm's. Any Ideas or do I need a new one?

This problem usually occurs when the in-tank check valve is leaking air back to the pump and the unloader is not working properly. Follow air discharge line from the compressor to the tank. This line is attached to the check valve (usually brass or chrome). A second smaller line also attaches to the checkvalve and leads to the pressure switch (unloader valve). After filling and shut off, you should hear a discharge of air at the pressure switch. If not, examine valve for possible mis-alignment with contact arm. If air continues to leak from the unloader valve, then checkvalve is leaking. Use universal replacement check valve if possible, check thread size. Parts are on ebay or www.toolpartsdirect.com. Good luck