Console Repair

Hi there, first post here.

I found a Sega Mega Drive in our basement and am working on restoring it. It turns on, but I have no audio or video.

I never used a cartridge-driven console before, so I want to make sure this is not user error. I need to plug in the cartridge before turning on the console, and then there should be a boot screen and eventually the game.

Is it possible for the contacts to be too dirty to allow reading the cartridges?

And then lastly, I had a peek into the maintenance manual I may need to exchange hardware parts. Should I need to; do you know any trustworthy sellers in the EU that could have parts compatible with the Mega Drive? I have been looking for a 53.2034 MHz +/-20ppm oscillater since it could be faulty, but couldn't find any shop that had one with that odd of a MHz frequency.

Any advice is appreciated. :)

Edit: Thank you all for your comments. On further inspection the contacts on the Mega Drive's cartridge-slot were oxidized. A little bit of sand paper did the trick. :)