You need to post some close detailed pictures of the banjo with the resonator off with a good close up of the rim and pot assembly. Not all of the 70s banjos were bad. You need to determine what exactly you have before you start changing things up that might not need changing at all. Nothing wrong with removing the neck and there are probably YouTube videos out there that you can view to tell you how to get that done. I would start off with some mild soap and water first to see exactly how clean you can get it with the pretty basic cleaning agents. If more is needed, go to one of the banjo merchandise suppliers on line and see what they have and go with that. (Banjo Ben, Bob Smakula, Elderly, Banjoteacher.com and others comes to mind.)  Same for any wood cleaning item if you want to work on that area as well. Just get the pictures up and there will be plenty of knowledgeable folks willing to help you out after they see what exactly it is that you have. I do see where you put three photos on your page but some of the neck and peghead would help as well.  Also if there is a serial number post that.  Should be on the back of the peghead if I remember correctly.  

Bobby

Thanks so much BobbyE, I initially posted with pictures but it failed so I'll try an put them here.

Serial number is 101617. 

More pix:

You might want to weigh the tone ring while you have it apart. Some of them were quite "light". Others considerably heavier.

Is the 5th fret inlay missing?

I used simichrome and an old t shirt to clean up my 1926 recently (see recent thread in here for pics). Came out great.

Not too many places left in NYC to buy banjo accessories. Guitar Center and Retrofret (in Carroll Gardens, Brooklyn) should have banjo heads. Guitar Center has only two different sets of banjo strings in the store. One of its NY stores had only one set.

You can get a head and D'Addario strings online from Smakula Fretted Instruments. Bob's a member here. Larger selections of strings are available at Elderly.com and StringsandBeyond.com.

The easiest big improvement in sound will be getting a new bridge. I, and many others, like Scorpion bridges. Made by Silvio Ferretti in Italy. But available here in the US from Banjo Ben's Warehouse, BannjoTeacher.com, and maybe also Elderly. Dotson bridges and the various models made by Kat Eyz are also popular and good sounding.

Tailpiece is next. I'm partial to the Kershner style. But I have a parts banjo with lots of 70s RB-250 parts and it sounds pretty good with the original Gibson clamshell tailpiece. I put some sticky-back velcro under the cover to keep it from rattling on the strings.

I second the suggestion of Simichrome polish for the metal. Use it once, you may never have to polish the parts again.

Definitely start mild with cleaners for the wood parts. Maybe use Gibson guitar polish -- the liquid in a pump bottle -- and a microfiber cloth.

If there's a musty smell in the banjo case, that's going to take a lot of work.  Start by sprinkling lots of baking soda in it then leaving it outside, open, in the sun. For several days. Vaccuum it out. Then consider spraying the inside with a dilute solution of white vinegar and wiping the interior to be sure it gets everywhere.  Then more baking soda to neutralize the vinegar, more sun, and more vaccuuming. Finally: I put some coffeemaker charcoal water filter packets in a musty case after doing all the above, and it's been odor free for a couple years now.  I keep them in the case with the banjo. One sits on the flange when the banjo is in the case. It used to have a smell and now it doesn't any more.

For that missing inlay, contact Tim Davis - https://www.davisbanjosandinlay.com - to find out if he has that specific piece in the exact size as used in the 1970s RB-250. Richie Dotson - https://acousticbox.com - is someone else to try. He's authentically duplicated most or all the pre-war Gibson inlay sets. While the 1970s Gibson inlay copies one of the pre-war designs, I don't know if the pieces are the exact same size. Richie might know.

Even if the piece is a drop-in fit, it's probably going to need sanding to bring it down flush with the fretboard, and that's tough to do with the adjacent frets in place. Maybe your banjo could use a fret job. Or at least a partial.

Looks like that banjo has been stored in a humid area by the metal "fogging", but especially what looks like rust on the coordinator rod threads. That will make the nuts very hard to loosen and then tighten up again.

I suggest a VERY small, judicious drop of something like good old Liquid Wrench to penetrate those threads to make it possible to turn the nuts without too much frustration. I more than half expect you want to remove the neck to clean it, and clean the rim where it mates up. Take photos of those coordinator rods now, and label each and every rod, piece, nut and washer so you can get them back in exactly the same spot they came from.

I expect you'll be able clean everything with the suggestions you've received. Rub GENTLY! Even Simichrome, which is pretty gentle, can rub away PLATING (like the nickel plate on your banjo. Many folks get by with Windex and a soft cloth for that "fogging" or hazing look.

I second Gibson polish for the wood.

For STUBBORN case stink, buy a little spray bottle of Ozone cleansing spray at an auto parts store. Car dealers use this get stink out of used cars. Don't get it on the banjo!

For decades I got all my banjo parts from the Stewart MacDonald catalog in Ohio. They're on-line and still in business. Basic bridges are around $10 unlike the boutique bridges which are $25 to $60.

You can get a replica tailpiece very similar to what came from the factory. Now made in Asia. Not very expensive. Tailpieces are very much a matter of personal taste though.

Good luck and have fun.

Thanks everyone, put in an order for head/strings/bridge with Smakula and I tracked down a neck removal video by Richie Dotson so a lot of progress thanks to all you.

I'll keep it gentle and track down a replacement inlay or just make my own--probably a bad idea to not fill it right?

Need to start playing more than anything else.

Thanks again

Breck

In case you need more, here's a video of a player named Johnny Butten taking apart a banjo. I have it starting when he gets to the neck.

In other discussions, some Hangout members have said they like Flitz metal polish. I believe it's one of the least abrasive products available. Maybe even non-abrasive. 

The issue with banjo parts is the nickel plating is sometimes thin. Some individual pieces are sometimes advertised as "triple nickel plated" which I guess is supposed to promise thicker plating. Best to proceed with caution.

Most of the photos I've seen of 1970s RB-250s (usually in for sale listings) show the metal having dulled after 40-50 years.