Drain backup and conflicting diagnoses
My house was built in 1987 and I bought it two years ago. I have had 2 sewer drain backups in 14 months and the second time, the plumber offered to "camera" my sewer line. The sewer pipe is 1/2 full of water for almost 30'. Ultimately, he says my drainage pipe is level when it should be sloped down. As a result, he says water and solid waste cannot drain correctly, resulting in the backups. He says my pipe cannot be replaced because there is no way to get the necessary slope and he is recommending I install a sewer pump for $6000. He would not give me a copy of his camera footage.
Needless to say, I paid a different plumber to camera my line so I could get a second opinion. 2nd plumber gave me a VHS copy of his footage. He claims the pipe is mis-aligned at a specific point. He wants to break through the floor of my house and repair the portion of pipe that is affected for $3400 (this cost factors in professional removal and re-installation of my laminate floor).
How can 2 plumbers be so different in their diagnosis? My house was built by a reputable builder and I am finding it hard to believe the sewer pipe was installed without the correct slope over 20 years ago, so am inclined not to believe the 1st plumber. But, could his diagnosis be valid?