Machine made a pffffft noise and started leaking water through the case.

Opened it up and it's leaking at the top of the boiler. After a little inspection I found an O-ring that's not sitting properly at the point of the leak (photo with top quality arrow attached).

boiler-leak.jpg

Before I get stuck in, what needs to be done to strip the machine down until I can replace this O-ring? I couldn't find many guides for disassembling the 2015 model.