I don't know what "top" is, but it looks like you've set it to DC-coupled, and the signal is only a few mV from perfectly centred, so the DC offset is ok, on the output at least. It does still look distorted, but it isn't toally flattened on one side like in the video. If you run it like in the video so the peaks are flattened, then reduce the amplitude a little at a time, does it become less distorted, like the peak amplitude on one side is limited?
I'm thinking that somewhere along the signal chain there's a faulty coupling capacitor, so the signal to the following stage is no longer centred. Presumably the service manual will have detailed enough schematics to let you locate the coupling capacitors. Tantalum capacitors can fail short, so checking those might reveal something.