Get familiar with your piston pump. Take out the owner's manual and check the list of components so you know what that they are beforehand. For instance, locate the crankshaft, valve assembly and cylinder head.
Grease as the manufacturer describes. This may include locating a grease fitting that is the central area for greasing the unit. If your piston pump has a grease fitting, simply take the grease coupler and grease gun available separately from your manufacturer. Wipe it off and place it in the grease fitting and pump. Be careful not to over lubricate and remember to wipe off your grease fitting after you finish.
Prime and start your pump. If this solves the problem, then you repaired the pump. If not, move on to Step 4.
Check for worn or cracked rubber, such as piston seals or O-rings. These are available as a replacement kit from most well supply retailers.
Install the piston well replacement kit as your manufacturer instructs in the manual.
Inspect your piston, connecting rod and belts. Service or replace a worn or damaged connecting rod. If you don't, it will put undue wear on the motor. Check belts for wear and replace those as necessary.