Water Leak. Aprilaire 550 mounted to furnace is leaking. Replaced water panel and confirmed no

Question

Aprilaire 550 mounted to furnace is leaking. Replaced water panel and confirmed no blockages on drains, cleaned all parts. Excess water is drained to a tray with a electric pump to waste line. Water is leaking from the outer case of the unit. It appears to much water is being put through the water panels and that water blows through the panel and leaks out of the case.What is the next thing to replace ? Thanks.