You may be able to seperate the panel from the PCB, and clean the Zebra strips, but I fear that might make it worse.
I tried on a spare, defective (“lines”) panel I had. No effect. Putting the whole thing back together is almost impossible, alignment and pressure level adjustment are factory level job. Moreover, no benefit in regard to the dead lines, so I would conclude they are consequence of failures in the active matrix panel. In a nutshell, just don’t do it.
Anyhow, the whole thing with the displays developing “dead lines” is indeed concerning for the preservation of these odd but beautiful machines.
I have three panels (non backlit), two of them developed these dead lines all of a sudden, starting from a perfect condition and after some hours of use following a long time storage. One unit is still perfect, bar for a single dead pixel. I’ve noticed it’s by chance an early unit, the cover lid featuring the two visible screws just underneath the slot of the retracted handle.
Without going paranoid on this, I would definitely be supportive if someone had the skills for developing and sourcing alternative solutions based on modern components.