Hey, bit late to the party but I use the Elma 1:9 too.
I have spent a lot of time trialing different strategies for cleaning parts. The best I have come up with is Elma 1:9 in an ultrasonic at about 40C for 4 minutes, then rinsing the parts basket in distilled water at 40-50C twice, the second time in the ultrasonic. For some but not all parts I use pure Isopropyl alcohol as a final rinse.
I have a gallon of the Suprol rinse here doing nothing but posing a fire hazard. Because I hate the smell of it and also, no matter what I tried it would leave some residue on the parts after drying.
I have an Elma S10, non heated ultrasonic cleaner, it works very well. I just run my tap to get the water temperature right, and considering the short cleaning times the water doesn't cool down much.
Could you please help me with the crown? I have these buttons, but what does that 9/24, 9/28 etc means? 9 or 8 are the thread size right? 9 is 0.9mm? But what is /24 and /28 and /30? Would that be 2.4 2.8 and 3 mm? I tried to compare a 9/24 to a 9/30 but the 9/30 does not seem to be bigger in any dimension? Not even sure if the right sized buttons are in the right container. I am trying to find a silver button for the silver case. Would be nice to know how the original looked like.