I took my NES down from the attic. It was in a box for probably a good 20 years. Easy. Plugged it in and it lit up, but games wouldn't play - gray screen.
Anyway, I took it apart, cleaned everything I could (according to youtube guides), cleaned my TMNT 2 cartridge and popped it in... after a few in/outs... it worked!!
So I played some of my old cartridges. Had to clean them all up and insert/take out/insert/take out etc. quite a few times with most of them. But they all worked! Game Genie even worked!
Anyway, I decided to get an EverDrive because ROMs are a thing now, and you can just pop in a card into the cartridge and have all the games ever created for NES playing on your original hardware.
I also got some wireless controllers. So I'm all set. This is such a fun world we live in.