Gave the Megadrive port a go tonight, it's definitely easier than the MSX2 version by far. Score #1 was easy mode, score #2 was normal, and score #8 was crazy mode.
1: 0541400
2: 0516800
8: 0051700
I know there's an established trick for repairing the thumbstick in these things that involves dissecting the switches to clean them out:
https://gamesx.com/controldata/neopadfix.htm
But I've found of the couple I've had come through my hands lately I didn't have to do that. If you desolder...
Serial #020213, sticker underside says use Pro Pow only.
Pic of the board: https://i.imgur.com/IWA8dvA.jpg
System was given to a friend as-is years ago, and they have given it to me in an attempt to fix it. I presume it was fed the wrong power supply at some point. I'm hoping to get it working...