According to Edith Reiter's 2014 book this instrument was completed on 20 September 2012. As of December 2021, this is the last heckelphone that has been completed and sold.
Howe & Hurd (2004) describe heckelphone #5023 as a model 36 voll cons.
As of December 2021, heckelphone #5023 is located in St. Paul (MN), USA, and owned by professional bassoonist Justin Windschitl, who acquired it in early December 2021 from Dolce Music International, a large music store in Tokyo, Japan. Dolce had purchased heckelphone #5023 directly from Wilhelm Heckel GmbH and kept it in unused, new condition since delivery.
Heckelphone #5023 is in outstanding condition and, after 9 years of storage in Japan, will finally be used regularly.