Possible sewer line failure?

I have a very old house, ABS drain system connected to an Orangeburg sewer line (I didn't know what that was until recently, ugh).

We had a drip at the connection to the orangeburg (a set of clamps). A plumber came in and said may be we will have to dig it up, but he wanted to try something cheaper first. He put a new set of clamps on and stabilized several things with new hangers and a bag of concrete where it leaves the foundation.

I had been noticing that there was still water on the basement floor and today I tracked it down to one of the cleanouts dripping from the cap. I could retape and refit the cleanout cap, but I figure that this can't be the real problem since the cleanout shouldn't be filled with liquid, should it?

I started to remove the lowest cleanout cap (the one that stares right down the sewer connection). It is filled with "liquid" under quite a bit of pressure. I tried draining several buckets worth with the cap slightly unscrewed, but it seem to still be filled with liquid....

I have called the plumber back, but it is Sunday... I want to make sure he is doing the right thing. What could be going on here? Is my orangeberg shot?

I does sound like like the Orangeberg is shot.

Sure enough, the downstairs shower just started spewing sewage....

It's time!

Get rid of that Orangeberg!