Hi Franco,
first the 250ies became quite little rarities because their production cost and quality was higher than their final price - and they are loved and hated: They can work perfect and you have never a problem with her - and there are little beasts you can repair any part in them and they still don't work properly (I have one of each ).
If you you want to know the production day of your lamp:
Look at the number at the bottom of your tank, there should be a number like 1523.
This means 15th week of year (196)2, the 3rd day
I haven't heard about a stovetop cooker for the 250, I have one for the 500 - it can boil up a liter of thick pea soup with sausages within 10 minutes - at a temperatur of ra. 10°C outside.
(If you want you can look at my report, even if it is german the pictures explain enough: http://www.pelam.de/petromaxfo…hilight=m%FCcken#post8311 )
I even percolated some espresso on it, it works quite good, but I doubt that the little 250 can give enough heating power for sufficient cooking.
The problem with your pump is your leather inside the pump tunnel.
Open the pump by screwing off the covering cap, take it out and put the leather piece into some oil (I use weapon oil, it has a little thinner consistence than regular oil). I have two or three leather pieces, one is in use, the others lie in the oil and getting soaked with it, that's keeping them smooth for years.
For quick use you screw the pump handle out and press it with the leather on a clean hard surface (I use a little plank of wood) for a few seconds. Repeat it a few times and when reinstalled, you will see that the resistance during pumping is much better.
For longtime usage and fun I urge you to buy a "Protectionplate HK250" ( http://www.pelam.de/product_in…7ea2d8ad0091815f457ee39bf )
I "lost" already one very old lamp because of some falling sock fragments melting down my welding sews. This little problem cost me almost one month for repairing.
The next tip I can give you ist to fill the tank with kerosene (ra one third or half) , shake it a little around and then filter it back into the kerosene bottle through a coffee filter (I took the littel petromax funnel (?right word?) and put a piece of filter over the lower hole).
After a few time you will wonder how much debris is in your tank; and these little metal pieces can choke your carburetor.
If I can see it right your glass has already some brown colour from using a damaged sock. If it is not molden you can clean it easily with some dish soap and warm water.
But always check your socks if they have bigger holes that spot-weld the flame to your glass and crack it.
Do you have as much mosquitos and little flies in Chile as we have in Germany in the evening? They like the light of your lamp very much and they can even be soaked through the carburetor through the sock, one member gave us a cuttingplan for brass-gauze, here is the link: http://www.pelam.de/petromaxfo…687&sid=&hilight=siebkorb
So, maybe this tips helped you a little to maintain your lamp.
Hope to see some lamp burning pictures from Chile
See you
Orthotiger