Depending on which model Mitsubishi is involved, there are additional considerations. Some production runs of late 1990s MGA SVHS models (but usually not their regular VHS lookalikes) have an obscure issue involving metallic shields that break down, bend, or corrode over time. This causes a short in the signal path coming off the video heads and results in the appearance of "lines" during playback that look very much like bad tape dropouts, ignition interference or mistracking. The models 760, 770 etc are especially prone to this. I've lost the link with the service instructions but the info is out there, google "Mitsubishi 770 false tape dropouts" and it should come up.
If cleaning does not help your problem with lines, your MGA svhs might need a pretty deep disassembly/realignment to get rid of it.