Thank you David!
I guess, ordering from Alembic wouldn't be the fastest way of obtaining a replacement in my case because I live on the opposite side of the globe:) Of course I'll do that if there are no other options.
It looks like jacks used in Series instruments are custom made for Alembic. There are no stereo jacks with 9 terminals in Switchcraft catalogue. However, I've seen such jacks online under different brand names like Philmore and Calrad. I assume I need a stereo jack with two isolated SPDT switches? Please correct me if I'm wrong.