Where to find OEM Dali Epicon woofer?

Again, before you order an expensive driver or ship your speaker, for the love of Pete, pull the woofer and hook it up directly to your speaker cable.  You need some due diligence here before deciding on a course of action.

Call Simply Stereo in Palatine, IL. Ask for Lee. Awesome guy, big DALI dealer.

Write to Dali tech support. https://www.dali-speakers.com/en-us/about-dali/technical-support/
They are a little slow to respond, but when I talked to them a couple years ago to discuss technical question Britta Olsen was pretty helpful. 

Hey John, check your private messages.  Just sent you some info that will hopefully help!