In case someone else are in the same situation: I bought the Octatrack Mk 1 with a loose button and opened it up. The button/switch is a spring loaded ball bearing type (don’t know the correct type). My faulty one, and this seems to have happened to quite a few on the Elektronauts forum, had actually physically opened up and the spring and ball fell out when I removed the panel.
Be very careful with panel removal as these switches seem to easily crack open if pushed sideways.
Anyways, I managed to access the switch and superglue the spring back in the top part. Then I carefully glued the button casing together with the ball inside. I have replacement switches on the way, but this works for now! I bought switches from ebay for 8.99 USD each, yikes… Apparently they should be Marquardt 1840 series but couldn’t track them down at a reasonable rate. Haven’t heard from Elektron yet (holiday season…).
Happy to support if anyone else needs to do this repair. And of course this voids warranty, but I guess most/all if these are too old in any case.
So far it seems great, just learning the basics but already bubbling over with thoughts of what to try :).