I'm sorry you're running into trouble with your scanner; very frustrating!
which the AI suggested might also be cause/exacerbated by light leakage
Which just goes to show how totally and utterly useless AI can be.
The streaking shown in the rather small examples seems to be RGB, so I see red, green and blue linear anomalies. My first guess would be that these are caused by a hardware defect in the actual sensor. So that would be a dead-end street and pretty much a one-way trip to the dumpster for this scanner.
Linear streaking in flatbed scanners is often caused by dirt on the calibration area, which is generally a narrow area at the start of the glass platen; film holders generally keep this area free and the scanner uses it to determine the minimum density. Dust etc. in this area will be included in the calibration for the scan, offsetting all color data acquired in that line. However, dust generally shows up as more or less neutral density, while in your case the linear defects are evidently colored and I suspect they have effectively a single pixel width. This is more consistent with a defect of the sensor itself. So bad news, I'm afraid.
You could try and dismantle the scanner and clean all glass surfaces, optics and (very, very carefully) perhaps even the sensor itself insofar as you can reach it without having to damage anything. But my first impression is that it's a long shot to try and fix this.