Drop p-trap, lay down tarp and attempt to clear secondary line. Using clean out will attempt to clear if cleanout is stuck will drop p-trap and snake through the p-trap. Will test for correct operation after clear. Removed p trap snaked secondary line. Pulled out quite a bit of sludge. Reassembled and tested. While cleaning up the mess under the sink left water running to ensure the line was clear. Collected payment from customer via check and emailed invoice.