Removing second stages from old DAs can be difficult at times. Many had the nuts peened in place and the support levers were bent. Both of these practices make the horseshoe lever and the second stage hard to remove. To make matters worse, the nut can be difficult if not impossible to remove without damaging the LP seat holder. Many are so badly peened and corroded that removing the nut results in breaking of the LP seat stem. Before Bryan had them reproduced, this was a death sentence for the old regs as replacements were hard to come by. This is how I go about removing a peened in second stage. It works the majority of the time but occasionally I still break one. It might not be the best way but it works for me, if anyone has a different technique, please share it.
Here is an example of a reg that has both the supports bent and a badly peened LP seat holder nut.
First I carefully bend the lever supports back straight with pliers, after you have them removed, double check they are straight and clean off any burs.
Hold the lever out of the way as best you can and with a thin screwdriver remove the 2 screws, at this point the lever will slide off. You can not get a full bite on the screws and sometimes damage them but replacements come with the service kit. At this point getting them out is all that matters. Often times I can work the lever off with just one screw and support removed.
With the lever and supports removed, gently unscrew the second stage. The threads on it are easily damaged so work it back and forth if it is hard to remove. Now comes the “fun” part, removing the nut. DO NOT try to remove it initially but rather screw it ON slightly then partially back off. Repeat this until the nut will screw most of the way ON, I know this is counter intuitive but what you are trying to accomplish is working the peen out of the brass nut threads. Trying to remove it at this point will just jam the 2 peened parts together; pretty much insuring you will break the LP seat holder. Remember, these parts are brass; they are fairly easy to break.
Once you have the nut screwed most (all if possible) of the way down you need to clean up the threads on the LP seat holder. For this you need a die. It is important to note here that these threads are 5-40 and not the more common 4-40. It’s easy to confuse the 2. Carefully start the die on to the thread and work it down as far as possible. Dies have 2 sides, one is intended to lead the die on so it has shallow partial threads, the other has threads that are more complete and come much closer to the edge of the die. Start with the side with the partial threads then repeat with the other side to get the thread cleaned up as much as possible. At this point the nut should come off easily. After you get the nut off and the second stage dissembled, run the die over the threads again to clean them up fully.
That should do it and remember to use the replacement nut that is in the service kit unless you just have to have the reg with all original parts. Hope this helps you accomplish this task..