Stubborn vertical line on gameboy screen

I picked up recently a pristine looking gameboy with missing vertical lines for cheap. I fixed it and placed a backlight mod. Two days later , three lines went missing again. Two of the lines fixed instantly with my soldering iron, but the third one refuses to be fixed
Is there a trick for stubborn lines? It's really frustrating having a visually perfect gameboy with this stubborn stupid line on the screen!!

 

I'm assuming you heat up the strip with a soldering iron like in the below video?



If so, it should be a matter of repeating this, could take quite some time, but it worked perfectly for me.

 

Yes I heat the strip with my soldering iron. The second part of the video describes exactly the problem I have . Seems to be unfixable according to this guy

 

I've only had failures when I cracked the corners on the LCD glass - Then there's nothing for it to adhere to anymore, no matter how long I applied heat to it. Otherwise, I've spend close to an hour with a panel before to get lines to 'stick'. About to get back into doing ore backlights, so I might have better insight in the near future.