how do you clean the milk frother on a delonghi magnifica s? it's all gummed up

You need to disassemble and soak the removable parts. Here's how.

1. Turn the steam knob to the off position and let the machine cool completely.
2. Unscrew the removable steam nozzle (part 5332169300) by turning it counter-clockwise.
3. Soak both the nozzle and the black frother attachment (part 7313219311) in warm water with a mild dish soap for 15-20 minutes.
4. Use a pin or unfolded paperclip to clear the small hole in the tip of the steam nozzle.
5. Rinse all parts thoroughly and dry them completely before screwing the nozzle back on.

If that didn't work, there might be milk baked into the internal steam tube. Run the steam function for a few seconds into an empty container to blast out any loose residue.

Heads up: Always run the steam function for a few seconds into a damp cloth immediately after frothing milk to clear the wand.