I'm in the process of restoring a la scala butterfly e61. I've pulled the machine apart and found some pretty heavy scale build up in the boiler. I've put it in a bucket of citric acid solution, which seems to have broken down the majority of it, but there is still some stubborn scale in the back. I'm just wondering if anyone knows of a more heavy duty descaling method. I want to ensure all the scale is broken down in the boiler, and in the tubes before I reassemble it.
You can get a "technician use only" descaler from coffeeparts. They also do a "normal" descaler.