I am having a major problem with my Amiga 600.

[Stedy]

Did you try flicking the little switch on the modulator?

[Stedy]

Back in the old days, I used some disk utilities to force my A600 into NTSC mode so that some games ran faster. I think the  old Assasins range had a few such tools.

Aminet had two possibles:

TINYpalntsc.lha    util/boot    1K    503    TINY pal & ntsc switching commands

 Kill2090.lha    util/boot    14K    182    Reboot, toggle NTSC/PAL, disable autoconf boards

Hope this helps.

Ian