Diagnosis
A leak from the pump body usually means one of the O-rings or seals on the pump head has failed. It's a common wear item, especially if the unit was stored without being winterized in freezing temperatures.
How to Fix It
You'll likely need a pump rebuild kit (often called a seal kit) specific to the AAA pump on this model. The fix involves disassembling the pump head. 1) Disconnect power and water. 2) Remove the four long bolts holding the pump head to the motor block. 3) Carefully separate the head—you'll see the piston and the seals. 4) Replace the worn seals with the new ones from the kit, applying a little silicone grease to help them seat. 5) Reassemble, tightening the bolts evenly in a criss-cross pattern. There are good video tutorials for "AAA pump seal replacement" that show the process.
If That Didn't Work
If it's leaking from a different spot, like a hose connection, just tightening that specific fitting might solve it. Check all connections first.
Heads Up
If water froze inside the pump, it can crack the housing itself, which is a more serious repair. A leak from a crack won't be fixed by just replacing seals.