Ok. Let’s try this again…RCA 9TC240 Alignment

[Penthode]

So the other scope was sick?

To ensure we are on the same page, please define backwards. Do you mean the x axis is scanning right to left? If so that suggests a polarity inversion on the x channel input.

And why is part of the trace darker? is the photo accurate to what you see or is there a shutter speed issue? If it a shutter issue, perhaps reducing slightly the scan trace speed will help.