Open lids thoroughly, check inlet and outlet baffles and tees, file cracks or rust

https://oscar-wiki.win/index.php/Dependable_Septic_System_Emptying:_What_to_Expect_from_Expert_Teams

Open lids carefully, check inlet and outlet baffles and tees, document fractures or deterioration, and repair seals to stop groundwater invasion and exfiltration that can overload the drainfield.