Lid O-ring

The lid O-ring is a small part with a big job. If it is dry, flat, or cracked, the pump pulls air and loses prime. You will see bubbles in the basket and weak flow.

Remove the ring, clean it, and rub on a coat of pool-safe lubricant when you clean the basket. Replace it if it looks flat or cracked. Use silicone-based lube, not petroleum jelly, because that can damage rubber. A good seal helps the pump prime and avoids an air leak.