You have one good power supply it sounds like. Use it, don't worry about the other one, it's probably not worth the effort to worry about it now.
For the carts, clean the contacts with 91% alcohol and something lint free.
For the power jack on the console, it probably needs to be replaced.
Forget about the original switch box and get a barrel type RCA to coax adapter.
If you are going to get your replacement parts from Best Electronics, there's a minimum order, so get everything you think you need in one go.
Console5.com has refurb kits that include the power jack and all the components that go bad overtime. The kit is cheap, so it's probably something you want to look into.
If you are going to use those two joysticks, consider rebuilding them with the Gold PCBs from Best Electronics. You also need new boots for them and possibly the retaining rings for the boots. The paddles may need new pots, so think about that too.
There's a lot of "ifs" involved in what you have and what you know about how well the stuff works, so it may come down to what you can afford to go ahead and replace and what can wait. Of course getting the console working is step one. Then you need working joysticks and paddles. You game carts are probably fine, they probably just need the contacts cleaned. The cart slot may also need cleaning. There are plenty of instructions online to help you with all the things you need to do or you can just ask the members here.
Don't let my list of things overwhelm you, most of this stuff is fairly simple to work out. If you can't afford all the parts for everything, just focus on the console, then worry about the accessories later. There are plenty of members who have extra working joysticks or paddles they will probably sell for a reasonable price.
If you don't feel comfortable with all the work involved, we can walk you through it step by step or there are members who will do the work for you if you don't mind the cost.
Edited by RamrodHare, Wed Dec 27, 2017 10:19 PM.