I have a Svea 123 R that has been with me since the late 70's and I had to replace the jet once during that time- used old fuel and clog it up.

A good safety tip if you do get one- use Fire Paste made by Coghlan's to prime it.

I bring a Plastic film can full of the stuff. just add a dime size amount to the base and light it then 20-25sec later open the needle.