Here we have a "P" Stamped 1926 Primus No.0 Stove. Have had it for a few years and decided to fettle it today. It looks good and complete from initial inspection, the problems started when I tried to dismantle it! Everything was stuck solid: I had to warm the pressure relief stub to shock the release screw into unscrewing. The filler cap wouldn't budge without risking damaging it. The pump rod was solid, as was the cap for the pump tube. The jet was solid and encrusted with gunk. After a quick bit of heat, the burner was persuaded to unscrew. Looking up the burner it was choked with gritty gunk. I then boiled the kettle and filled the tank (with a squirt of dish soap to loosen up any deposits) through the burner upstand and then the basin around it, allowing it to barely trickle out of the pressure release stub. I left it sitting for 10 minutes to do its thing. I mananged to persuade the filler cap to unscrew and was faced with a drift of crud from inside! Flushed/shook with boiling water and managed to swill all of the gunk out of the tank. A bit more boiling water and the pump cap was persuaded to unscrew with a bit of effort. I managed to get the pump rod out and found it was fossilised pump leather that was stopping it The NRV Head was buried in rock hard crud/leather. Judicious scraping with a bit of welding rod and regular flushing with boiling water and it was all cleared out. The burner I heated and quenched a couple of times to shake everything loose and remove the bulk of the hard crud. I managed to get the jet scraped clean enough to work the universal joint tool onto it and remarkably it unscrewed with minimal effort! The jet was persuaded to be pricked clean with a bit of effort I then boiled the burner/flame ring/preheat cup for 15 minutes or so in some water with a teaspoon of cream of tartare - my preferred gentle method for burners. Afterwards I heated the burner once more and gave it a blast of air, a cloud of rubbish came out of the burner, job done. A good scrub with a soft wire brush cleaned everything else up as required. Reassembled with new leather and viton all round. Preheated and fired up without issue. Flame is perhaps slightly off-center but it doesn't affect performance. Lovely running little beastie. I will address the rust on the legs/pot stands before it gets any worse A light scrub with a soft cloth and a rub of machine oil preserves the patina, job done for now Alec.