I've had a shower that drains extremely slowly. I added an air admittance vent. After doing so, apparently I was too rough on the connections b/c the shower started leaking like crazy the next day. Luckily the floor in the bathroom was already ripped out b/c of the toilet leaking 2 weeks previous! Behind the shower,the water was evident at the top of the elbow. It did not leak from the work I did the previous day. Apparently it's been leaking just slightly for a while (as you can see all the rust on the concrete below) and I aggravated it just enough to open the flood gates.
Now I've gotten new ABS pieces to replace the old ABS and that old iron(?) elbow. However, I can't get the elbow off AT ALL. I've been using an extremely large set of channel-locks and WD-40 Rust-Release Penetrant but no-go. Additionally, the brass(?) drain assembly it's all connected to shifts as I attempt to twist the elbow off.
It also doesn't even look like I've got enough clearance to get an ABS elbow in there in the first place. Is there going to be a way to do this without taking the entire tub out?
EDIT: With the old work still on: