For some reason my left eye piece is glitching. I just bought it today and popped in mario tennis. but the left screen...

Hello. Like S W said, you need the zapper. You also need a CRT TV (Tube TV) to have the gun to work. It will work, for example it will shoot but it will never hit anything if you are playing on a plasma tv or such. But you can find CRTs at a lot of garage sales, i got mine at a garage sale for free. Happy Collecting!

Hello. You have what may be a broken 72 Pin Connector. You May want to get a new one or it may be dirty so just clean it. The Game may be dirty too. Cut off the green part of a sponge or get scrub pads from the store too clean your pins. If it does not work, Open your cartridge and clean the pins well with a small ammount of counter top cleaner. brish it on and then take a towl and wipe the cleaner off. Then put the case back on. Please only do this with the game.

Dont Worry, both of mine have that too. It wont affect your console at all.

they are not the greatest controllers, they break easy

Clean the laser, it might be dirty

The AC adapter might be wrong, make sure its for the GENESIS 1 ONLY, there are the 2 and 3, they dont work on the 1

its probably busted or dirty, clean it

not an expert but try to unplug and plug in the AV or RF cable, if it doesn't work, get 3rd party cords, happens all the time to me

EDIT: Sorry about the wrongful information, i just edited what i know now. Also Please Beware im a young collector, so i really didnt think when i said that. Well, its fine to use it but i really dont like to use it but, sometimes i have to. But its not going to hurt to use it a few times, but just be warned there is a possibility of rusting. It really shouldnt go on, but it gets the job done. What i like to do is use a scrubbing pad, a and clean the pins by scrubing it gently. Try not to blow on them too often since again, it could rust from moisture. If it doesnt work, take apart the cartridge and use counter top cleaner, trust me, it works well, my friend at a retro game shop told me it, and it WORKS. if you tried everything, it may be that the board is shorted out and will not work at all, that means it is dead, hoped that helped