Use a pipe wrench to loosen the cap on your main line drain pipe before you open it entirely.
Drain clean out cap stuck.
Https amzn to 3lszden make your own sewer.
Remove the cleanout plug with finesse and force photo 1.
Slide both couplers onto the old pipe then slide the vertical.
After this i used the cut off wheel to slice away portions of the cap until i could get near the inner.
Once it s safely removed use the old fitting as a guide to cut a replacement section of pipe and clue up a new.
If all your efforts fail you may have to cut out the fitting and install a new one.
Open the cap and let the buildup drain out quickly open the cap and step out of the way.
I let the water drain out then i cut out the nut using a metal cut off wheel rotozip.
Heat the cleanout plug and fitting clean away any.