after playing mega man 9 and mega man 10, I became interested in retro games. I recently bought a retron 3 to play nes, genesis, and snes, but I've encountered some problems with nes games. I think the circuit boards in several of them r dirty. what would be the best way in which to clean the boards of these nes games? I've seen some cleaning solutions specifically for this, but they seem like a rip off or something. it's like they're selling u rubbing alcohol for $20 basically.