Lumogaz 400 is a Campingaz lantern. It uses the old type pierceable gaz cartridges but still available. These can be Campingaz brand or another brand of same cartridge which are normally cheaper & work no probs.
Newer Campingaz lanterns use screw in cartridges. Check yours uses old type pierceable by the sharp point in middle of screw underneath.
For mantles just put “Campingaz mantle” into ebay search & you will find. Or your local camping shop will probably stock both cartridges & mantles.
The piercable 400 type cartridge wasn’t around for long. However I think you can double up two 200 type cartridges into the holder and just swap one for the other when one runs out, I saw a picture of this somewhere but can’t find it now!
As for a mantle, I have Lumogaz “R” from about the same era, centre tube feed with the mantle over the top like yours. Looking at the Campingaz/ Coleman pack of replacement mantles I can see ten of the lamps take Small size mantles, with five Medium and five taking Large. I think your lamp will be small size but if you would like to measure the width of the top mounting point, just under the arrow head shape on the delivery tube, down to the notch for the lower mounting point, I can compare with my lamp. So it’s width of the tube and distance between mounts, I prefer Metric please.
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