Despite all the other comments recommendations the only thing that worked for me when using a hair dryer:

- use the thin nozzle for the hair dryer

- used some kitchen tongs to hold the earbud

- I needed 60 seconds before the glue was hot enough, slowly rotating the earbud, 30 seconds per rotation.

- here’s the key bit: use some grips wrapped in cloth (as to not scratch the earbuds) and squeeze the headphones lengthways from top to bottomin order to slightly bend the case. You may notice the gap widening enough to get your tool in. This was the only way I could get a wide enough gap to stick a Stanley/xacto knife in between the case and Jimmy it around. The first one I got hot enough to squeeze with my hands, but the second was tougher, though it may have needed a bit more heating.

Without this squeeze method I wasted a good hour absolutely scratching up my right earbud.