Aww, a fire! That's terrible.
FYI: That Aiwa is a rebadged Panasonic. I have a Samsung, which is also a rebadged Panasonic. And I believe the JVC is a rebadge, too. So anything you see online about multisystem VCRs is essentially referring to the same unit.
A pure TBC won't help.
However, I do have a special PAL>NTSC / NTSC>PAL TBC. It's composite, and I'm selling it for $350. (You can always buy it, use it, resell it.) This is for converting without the aid of the PAL>NTSC circuits inside the VCR. You'd play PAL and PAL, and the TBC converts.
The internal conversion circuits might be fired.
It could also just be a wiring issue.
PAL/NTSC VHS hardware can be temperamental.
B&W image is a typical problem, with many solutions.