Before bidding on a lamp, make sure seller has pictures.  Note that all parts are there.  If not, you are either going to end up buying it  "for parts" or have to get them elsewhere.  They are available from other sellers,  like Bob and Bob; or see other guides on buying lamps.

 Can you see if it has an orifice? ("jewel tip") in the middle of the reflector?  These are sometimes hard to spot in pictures.  You may have to ask the seller.  Also, make sure the wing nut is there, too.  And. of course, the obvious stuff; reflector (still has its finish?); bottom; hat clips (Autolite has 2 clips--a loop at the base and at the top); water reservoir (the main part with its valve lever), and  its cap.  Sometimes the cap works loose and falls off.

  Also, the BIG one: ask if the base (Carbide chamber) can be easily unscrewed, if it isn't shown  disassembled.  If the base cannot be removed by hand, and there is still carbide in it (it will weigh a bit), STAY AWAY unless you want it for parts.  In a frozen condition, with old carbide, the lime will have corroded the threads together, and eaten on the chamber until you have a myriad of cracks and paper-thin walls. Getting it off without it completely disintegrating is a PAIN.  I just fixed one like this; it must have had a dozen cracks, and I brazed it for strength. I spent more in brazing rod than the chamber was worth, unless it's very old and rare.

  Most chambers fit most lamps, except JustRite.  Except for orifices (JustRite calls them "jewel tips") and wing nuts, they have all proprietary parts, but are the most common. 

   As said before, new springs and flints can be found in 98 cent butane cigarette lighters; you may have to cut them to make them fit.

    Spark Wheels get dull; either replace or sharpen them with a Diamond disk on a Dremel tool.

    Reflectors can be easily reshaped if brass or copper. A small  replating kit for copper and  nickel , requiring a 3 volt source, is available from dealers in antique radio repair parts, like AntiqueElectronics.com in Tempe, AZ; or just seach eBay or Yahoo.

The washer at the base of the carbide chamber crack with age.  Just replace it with another one or find a similar gasket at a hardware store. 

There is also a green felt filter at the base of the water chamber. These hide beneath a brass retaining clip--make sure it is OK, too.  They either disappear or get clogged.  I have seen vintage boxes of them go for $50--just find a better one  in another lamp  or cut one of green acrylic felt and save a lot of $$.

  The rest can be cleaned up well with a Brillo pad and cleanser. Polishing with a bonnet and rouge is a good option.  Use a wire wheel or brush  on the worst of it. A Dremel and its small bits really get the corners.

  Lime on brass and copper  can be removed by soaking in vinegar.   Muriatic acid works best; wear GLOVES, and soak for about 5 minutes or so; rinse well.  It will reduce a lot of the corrosion, too. Do NOT use on rusty  steel reflectors--these require Naval Jelly for 1/2 hour, then brushing, sanding, and replating. Yuck! Best to bite the bullet and buy another one.

  Small dents can usually be pressed back. 

 Small cracks, holes, etc, can  be repaired with 2% silver solder.  I use Harris 45 silver braze; it requires a lot of practice and a MAPP gas torch, but will rebuild cracks, holes, and missing brass. It almost perfectly matches brass or copper, too, unlike solder. It is available for $13 per oz. from weldssupply on eBay. (Be SURE to get flux, too!! )  File or Dremel the beads back. Sand them down and polish them.

   When done, a light coat of a clear anti-UV spray (inside and out) will help preserve your 'piece, unless you want to really use it,  in which case don't spray the reflector or anything near the orifice, which will get hot and burn the coating.

  Enjoy!!