After confirming that the main line and the city/county portion of the lateral from our backwater valve to the street are clear, they camera'ed from the backwater valve back to the house. It revealed what is believed to ba another backwater valve in my basement. This is a 95+ year old house but sewer line is not as old but still may be old. There is a mysterious recess in my basement floor with what appears to be a cap to what I thought was simply an old cleanout. I've owned property for past 25 years and never paid attention to it because there is a new cleanout above the floor somewhere else. The county by the way would not snake past this valve and suggested I or someone try to open it and remove the clog. I enclosed a photo below and ask for help in knowing whether this looks like it is indeed a backwater valve cover and if so how would I remove it. I want to simply snake the drain from the house side out to/past it, not caring if I damage the flapper, but I don't know if that's a good idea. (As mentioned there is a newer (15 yrs old) backwater valve in the yard). Would you recommend snaking to it, past it, or jetting the line. It has been ruuning slow for a few weeks I believe and my daughter just informed me of that.