Bei thelostcoaster.wordpress.com auf Seite 9 kann man u.a. eine zitierte eMail von Wieland Schwarzkopf lesen, wo er das -was André B. schon schrieb- bestätigte: Ja - ein Schwarzkopf-Buch über die Anlagen und seinem Vater:

Hello,
your email is very interesting, because nowadays only few people knows about the JUMBO JET. For detailed infos you should contact Andre Blunck, he is just doing a book about our company, the rides and of course about my father.
As far as my memory is still in function, we manufactured 5 JUMBO JETS. The one from Cedar Points I bought in the early `90ies from a citypark in Malmoe/Sweden and rented it out for a one year operation in Prague/Czechia, after for several years to Poland. In 2002 the ride was totally refurbished and sold in 2003 to a citypark in Nizhny Novgorod/Russia, from there it were sold last spring to a citypark in Minsk/Belarus.

Hope it was helpful for you and good luck to get the rest of your required infos by Andre.

Best regards
Wieland Schwarzkopf

Gruß
Ludwig