that model of snes doesn't need a mod, just the right cables. you'll need a rgb cable that uses csync. here's a link for some more info.
https://www.retrorgb.com/snescsync.html
It looks like a sync issue too me, it's weird that you have the problem using composite. I normally see this with rgb when the sync isn't properly connected. I suspect a problem with a cap or the video chip. I think a good test would be to try RGB using Csync. if it still doesn't work most likely it would be the video\rgb chip.
On a Atari 2600 I'd say the rarest I have is Smurfs Save the Day and Snoopy & the Red Baron with manual. What's neat is I got these two games and a handful of others+complete system with controllers and two semi boxed paddles for $30 at a auction.
Happened to me also, I ordered the JPN and got the EUR version. I haven't opened mine yet but don't think I would be willing to go through the trouble of sending it back.
1. Astro Warrior
2. Shinobi
3. Hang-On
I didn't get to play many sms games expect for these. Even though I didn't get to play many, these are some of my favorite games especially Shinobi and Astro warrior.
Big thanks for the sram dumping feature on the SNT JB firmware. Something I find really entertaining, is I have a SUPER UFO due for delivery today. I'm sure I can still find a use for it, seeing the JB can't write back to the cart.
I already have a a stock genesis with killer rgb, and I still want a fpga solution. Not having to rely on my framemeister or PVM has its appeal, for me at least.
I don't seem to be getting that glitch on the US version of Pokemon Gold, at least not on the title screen I haven't played much beyond that. Is it consistent?
edit: This is using the US Super Gameboy
Faulty? Since you sent Analogue two different Nt Mini's did they actually find anything wrong with them?? I'd test pal composite myself but I'd have to buy a special vga to composite adapter to do so. Have you tested running composite straight to a crt or trying svideo??