It’s been a few months since I took my ROK apart for cleaning. It’s so easy to do, I really should do it more often. Leaving it for a long time can make the cylinder hard to get out. You’ll find the inside of the main aluminium frame probably has some oxidisation. Mine does. Just wipe it with a damp cloth – nothing abrasive. You won’t get it all off. You can use a mix of white vinegar and water. I just use water. Wipe the coffee residue from the plunger and o-ring too. Store your ROK with the filter seal out to allow better drying. Always dry your ROK thoroughly after use.