Yes, I believe you can. I've opened mine up because my earphones are
not working also. my unit is out of warranty so I didn't worry about it. There is four little screws holding the unit together inside the battery compartment. Remove the two padded tape and it will reveal the
four screws. Then loosen the two black plastic nuts,which hold the
earphones and coil to the back of control box. After everything is
loose take a butter knife and lightly pry along the seem by the top
side of the unit. Be careful,there is on o-ring which is compressed
along that seem. The whole top will slide like a cassete. you also
will need to feed the earphone and coil wire upward as your removing
the cassete. This is so you don't yank loose wire from the cicuit
board. you will then see where the earphone is connected to on the
board. that is where you will need to solder the new earphones to.
The rest is self explainatory however, after putting it back togeter
you need to make sure that the compression fits are good after tightening up the two black nuts (earphone&coil)so it don't leak.
If you can achieve this, mission accomplished!
hope this helps!