The start: Two broken Gaggia Coffee machines from my local Craigslist equivalent. One leaking, the other one missing a few parts, bought by the previous owner to repair the other one. He gave up on the project, and I got it for cheap.
I documented the whole process with a little timelapse video.
Step 1: Disassembly
Taking the whole thing apart, while labelling all cables and hoses. Penetrating oil was used on all bolts.
Step 2: Cleaning
As you can see, there was a lot of decalcification needed. Most of it was removed mechanically, but some chemicals were used with caution.
Step 3: Repainting the Casing
Rust was removed with a steel brush, and sandpaper. Hammerite white paint was used to repaint rust spots. Not a perfect match, but good enough for an appliance.
Step 4: Filling the Holes
Liquid metal was used to fill deep corrosion holes on the boilers sealing surface. After carefully removing any caulcification, it was applied carefully, taking care not to leave any bubbles. The surfaces were carefully sanded flat. I was not sure if the liquid metal was going to survive the temperatures, but it held up fine after half a year of use.
Step 5: Resealing
All O-rings were replaced with new ones. On reassembly, some high temperature sealant was used on the boilder seals, as well as teflon tape on all threaded fluid connections.
Step 6: Reassembly
The whole machine was reassembled, with the labelling of connections proving very helpful. After filling the machine with water, I ran two tanks of water through the system to clean out any residual cleaners.
Step 7: Make Some Cappucino
Well, of yourse it took a while of setting up the grinder and the coffee pressure to get good crema.