These are Alps encoders with 30 detents and 15 pulses per rotation.

I believe the part number of the original or at least a suitable replacement to be EC11E15244C0 , but I can't find anyone who sells it. Mouser sells part number EC11E15244C0 which is exactly the same as the other part number except for travel which is 1.5mm instead of .5mm. You may still be able to get it to work though. You would have to stuff the shaft hole with 1mm of material to make clearance for travel.

Stu
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If you want it to break, buy Sony!