I've had a Seva 123 since they were $13.95 retail, 1969, it has never failed !
Lots of comments here and I have not read them all so I don't know if this is a repeat.

About the only thing that will affect your stove long term is if you let it burn out, ie
run out of fuel while in use.
There is a cotton (?) wick in closed in the actual burner head, it is what draws the fuel into
the burner to be vaporized. If you let the stove burn out this wick will become charred
and that will affect the fuel flow. So in short don't ever let it burn out, refill before each use.

A couple other things.
You need a better wind screen, they are easy to make.
Make it tall enough to be within 1-2in of the top of your pot, fitting within about 1 in of the pot sidewalls.
Only enclose the stove about 75% so it will not overheat and pop off, flame thrower !
To pre-heat my stove I hold it over a candle or use a sm. plastic eye dropper to suck up some reg. stove fuel. I have even used my Bic to pre-heat the stove.
When you calculate the total weight of this stove with a fuel bottle it really is not any heavier than the
new fancy wiz-bang stoves on the market. It requires less maintenance and has no plastic parts to fail.

Take care of it and this stove will never fail.