So my kitchen sink (which is a stainless basin style single drain with disposal and dishwasher tied in) is plugged. I’m by no means a plumber but have my fair share of plumbing experience. I’ve tried clamping dishwasher drain and plunging, hot water, removing disposal, checking trap, all with no luck. The only way sink or dishwasher will drain is by running disposal, which I know can act like a pump to push water trough a blockage without clearing it, so I figure the blockage is downstream of the trap. So I have a cleanout directly below the trap, so I think, perfect, open the trap to snake out the clog, only when I pull the cap, 1 1/2” inside the cleanout is a solid plastic, almost like a knockout blocking the cleanout from being cleaned out. And here lies my dilemma. Anybody with some solutions? Oh yeah, this is my first post, so if I’m out of turn or in the wrong forum or whatever, I’ll apologize now. Thanks for your help.