We're all talking 'past tense' regarding the Svea 123. You can still buy it brand new and the little pump is an Optimus accessory for the Svea and R-8.
I've got a pre 1965 Svea (no self cleaning valve, but came with a "pricker"), a Svea 123 (123 has the self cleaning valve), and an R-8 Hunter. The R-8 has exactly the same burner/valve assembly as the 123. The old Svea (not the 123) puts out a third more heat than the 123, probably because there is no self cleaning needle in the generator chamber. If you ever want a Svea, look for the older one...Ebay is a good place. I've never payed more than $30 for a Svea....the R-8 was $5 at a garage sale, in perfect condition! I've reconditioned all these stoves to new, with all accessories, except the booster pumps. They are by far the most dependable stoves in my collection....and I have a pile, old and new.

Regarding the pressure relief valve/factory flame thrower....yes that happens, but usually due to people putting the stove behind a wind shield or by baffling the stove to force more heat output (it doesn't need more!!! The things roar like freight trains). Two things happen, either the pressure relief valve does it's job and shoots out a fire ball, or, the stove base/tank expands into a 'football' shape and the stove springs off the ground! The place I use for parts has stories of all kind of interesting mishaps, involving all makes of stoves.

The only things I know you don't want to do with a Svea is 1. don't shield/baffle it for more heat. 2. Don't let the tank run completely dry...you'll carbonize the cotton mop/wick inside. 3. Don't use it for 2 gallon, chili cook off pots....really heavy pots will break the pot support. (i machined tiny brass rivets for one of mine...you could park a car on it)

Optimus stoves, old and new, can be reconditioned to new. The best source of parts and knowledge is this place:
http://www.packstoves.com/optimus%20pages/optimus%20svea%20stove.htm

Another good source of knowledge and maybe a used stove or two is:
http://www.spiritburner.com/
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paul, texas KD5IVP