Many Air Bubbles In Filtered Syrup

Potential Causes

Solutions

Mouth of the input hose is not fully immersed in syrup or the hose is clogged. Clean the hose. Then make sure the mouth of the hose is fully in the syrup.
Loose inlet manifold, damaged seal between manifold and seat or damaged o-ring. Tighten or replace
(Here are parts)
Diaphragm is ruptured Replace the diaphragm
(Here are parts)