Use a pipe wrench to loosen the cap on your main line drain pipe before you open it entirely.
Drain clean out cap stuck.
Once it s safely removed use the old fitting as a guide to cut a replacement section of pipe and clue up a new.
Slide both couplers onto the old pipe then slide the vertical.
Dousing the plug several times with penetrating catalyst lubricant often also called a rust breaker is another way to.
Open the cap and let the buildup drain out quickly open the cap and step out of the way.
Heat the cleanout plug and fitting clean away any.
If all your efforts fail you may have to cut out the fitting and install a new one.
Https amzn to 3lszden make your own sewer.
Make sure your reciprocating saw has a metal cutting blade before you turn it on otherwise you re in for a difficult.
After this i used the cut off wheel to slice away portions of the cap until i could get near the inner.