Start with your torn down 523.
Place the front plate of the stove over the tank. Note there are raised thread bosses on the tank so you will have to place the plate over the tank then slide the tank into the stove frame. You want to use the lower set of holes. After you get the tank in the frame install the screws and snug them down. We will come back to these and adjust them later.
Just in case you are wondering why there are 2 sets of holes I have interviewed people that claim there is a heat drum attachment that would fit these stoves but to use it one would have to move the tank to the upper set of holes. I have never seen one nor have I found any documents that support it but I have been told by several WWII vets that they used such a thing.
Next we move to the valve assembly. After you place the F&A tube on the valve assembly you are ready to install the valve. Just a couple of things about these F&A tubes on theses stoves. 90% of the time these are what is wrong with a 523. A lot of people would use leaded gas in these stoves causing a lot of gunk to form in the inside wall of the tube after long term storage. It is very important to make sure you have air flowing through the outside holes of the F&A tube. Countless times I have had to un solder the cap and clean out the tube and solder the cap back on.
I ONLY use red thread locker on all valve threads. Lantern, stove what ever. I know there are other things out there but the way I figure it they used it in 1943 when the stove was built and it never leaked. I always do a test install before I apply the thread locker. This will give you an idea of how many turns it will take to tighten up. Make sure you have the threads really clean and apply a fair amount of thread locker on the valve threads. Make sure not to get the thread locker down on the top nut for the F&A tube or air holes. Then thread the valve into the tank. Most of the time 4 turns is the magic number. Make sure that you turn the vale so that is stops at an angle pointing toward the inside of the stove.
Now we move to the valve shaft and packing.
Here is the correct arrangement for the valve packing and spacers. Small spacer goes on first, then the packing then the larger spacer.
Now place the packing nut and the valve wheel on the shaft.
Slide the valve shaft and the packing into the valve assembly. Turn the valve shaft just enough to get it started.
Push the valve packing and spacers into the valve assembly and thread the nut as far as you can by hand.
Now follow this close. Place a 9/16 wrench on the valve packing nut and tighten it down while turning in the valve shaft. NEVER TIGHTEN DOWN THE PACKING NUT WITHOUT MAKING SURE THE VALVE SHAFT IS ALL THE WAY IN. Once the valve shaft is all the way in tighten the packing nut down until there is a fair amount of drag while turning the valve shaft. You will have to come back and snug this down again after the stove has been run a few times, they WILL loosen up and suck air before they start to leak. This will cause the burner not to burn correct.
Now we move to one of the most critical parts of the of the stove. The vaporizer tip cleaner rod setting. It is very easy to mess this up and damage the tip rod. If you don't thread the tip rod far enough into the eccentric block you will bottom out the top of the tip rod against the bottom of the gas tip when you turn the tip cleaner. If you don't thread it far enough in the block the tip rod will not come through the gas tip. If you did not move the jam nut during removal then thread the tip rod in and lock down the jam nut. If it did get moved here is how to set it. Thread the jam nut up the tip rod.
Thread the tip rod into the block and place the vaporizer on the valve without the vaporizer nut and turn the tip cleaner arm up. You can see in the next picture the tip cleaner is not through the gas tip. Remove the vaporizer and thread the tip rod out a thread and place the vaporizer back on the valve. Turn the tip cleaner and look for the tip to come through the gas tip. Repeat this until you see the tip cleaner come through the gas tip. Once you see the tip cleaner through the gas tip hold down on the vaporizer body and turn the tip cleaner and make sure the tip rod is not lifting the vaporizer up. Most of the time if you thread the tip rod all the way in the block then back it out 2 turns it's close or good. But always check it.
From here you reinstall the vaporizer nut. The burner. The pump and the legs. Tighten the burner hand tight, that's all it needs. The only other adjustment that may be needed is the position of the tank in the frame. If the burners are not centered in the frame loosen the tank screws and rotate the tank till the burners are where they are centered in the frame and tighten down the tank screws.
You have assembled your 523 stove!!!
Now it's time to fire it up!!!!
I hope this helps.
ICCC member # 1154
Still learning how NOT to do things.