Hello, Can anyone please tell me what brand and type of stems these are? I would really appreciate it. Thanks, Anthony

Shortest possible detail: I'm living in a roughly 20 year old house in minnesota apparently designed by idiots. If I end up with some $10,000 repair i'll probably end up homeless so i'm trying to see whats possible. Years ago there was a sewer backup problem, that i'm back to trying to fix again because something got worse after a basement flood. We ran a video camera down the sewer originally at the time and I remember seeing a series of 3 clear door-flap things that the sewer camera would push through - seemingly an anti backflow valve meant for water to go out, but not be able to readily flow back in. The third one never opened. The guy tried smacking it hard enough with the camera to potentially break it even and it still wouldn't open/seemingly seized. (this was when it was literally only 6 years old or so as a house already past the near worthless '2 year house warranty' as it was) That answered why I had sewer backups at the time but I couldn't do anything to fix it because I was hanging on by my fingernails in life so I just stopped using the dishwasher or washing machine at home since that was the only time there was ever a problem. At the time the plumbing guy "guessed there must be some kind of access port from the top that lets you clear out or move those flaps manually" if we were willing to yank up all the carpet, but since I had the room it seemed to be in full of storage with nowhere to conveniently move it I couldn't chase after it at the time. So I had a flood last fall when the septic pump failed out of the blue without warning and i'm guessing some dirt or something got additionally flushed down the floor drains. Carpet was damaged and the worthless homeowner insurance is stiffing me for everything. So I pull up all the carpet and... there's no access anything, or not really. There was a plastered over access port of sorts so a friend helps me chop through it, standard screw top that I see elsewhere, and a pipe that goes straight down and has the sewer feed in from the side. But there is no way to access the TOP of those three flappy valves that seem to be before this, like even if something could be shoved down from THIS side the valve was pretty dang well seized from pushing from the other side... So now i'm being kept awake at night sick wondering if this means someone has to jackhammer through the floor to even reach those things. I'm half wondering if there's some way to just break the third backflow valve but it doesn't seem like it's right at the end of the access port, I mean it's not within inches/i'm not sure how far up the pipe it is but it's not "right there". There's no top access for the flappy-valve like the original plumber guy thought there would be. And now the sludge from the sewer backup that washed down the floor drains seems to be causing renewed problems - a sudden flushing of water down the drains (pressurized from the washing machine, what would originally cause the problem) doesn't work because that third flapper valve was the problem originally. What ARE even the options?