In this video live recording Jürgen uses a late 1962 Fender Jazz Bass with veneer rosewood fretboard. He converted it into fretless after buying it in 1989.
So, while this bass guitar is not Jaco’s, it is indeed a close relative to Jaco’s “bass of doom” which is a late ’62 Jazz Bass as well.
Finish on the board is boat epoxy/polyurethan.
Tuning is standard E/A/D/G