Just a few years after the company was founded, the product range was expanded to include electrical and mechanical organ parts, including the slider motor (1959), of which around 125,000 units were manufactured and delivered all over the world by 2003. In 1964, the product range is listed in a catalog that is sent to all customers. The organ parts are listed with 3 or 4-digit numbers and divided into 7 groups. The appendix to the catalog mentions “half a hundred” employees. A glance at the HEUSS archives shows how large and widely distributed the customer base already is at this time, so that it is fair to say that the OTTO HEUSS ORGAN PARTS company is well established. The following year, the company founder passes away. Otto J. Heuss continues to run the company alone. In a pre-war building directly on the corner of Amtsgerichtsstraße and Langgasse, where a car repair shop was located until 1959, Otto J. Heuss manufactures sought-after punching tools under the company name INTEC. Even today, this building is still referred to internally as the “tool shop”. Another global corporation also has its products manufactured at OTTO HEUSS: switching elements for televisions are manufactured and assembled for Philips. At the beginning of the 1970s, another workshop with a paint shop and woodworkshop is built on the western outskirts of Lich, Am Fuchsstrauch, but is only used by the company for a few years. The 1973 oil crisis also had an impact on organ building, particularly on exports to the USA.

Stefan Otto Heuss (*1964; trained as an organ builder with OTTO HEUSS and Werner Bosch in Niestetal-Sandershausen 1981-1985; followed by further training with Martin Ott in St.Louis/USA) joins the company in 1986 and becomes second managing director in 1990. The publication of catalog no. 5 in June 1992 represents a milestone. The significantly expanded product range is presented in two languages (German/English) for the first time, an important sign for the rapidly growing international clientele. In the previous two decades, Otto J. Heuss had already represented the company at numerous national and international trade fairs. In 1997, Stefan O. Heuss passes his master craftsman's examination. His masterpiece is a chest organ with manual bellows. The chest organ can still be played today in the OTTO HEUSS showroom. Otto J. Heuss dies on 04.01.2000. Stefan O. Heuss continues to run the company alone. Initially, one focus of his activities was the in-house production of manual keyboards. At times, grand and upright pianos are also supplied to the global market. 2003 marks the 50th anniversary of the OTTO HEUSS company. Catalog No. 6 is sent out in 2007. At this time, it is already clear that this may be the last printed catalog. The Internet is becoming increasingly important. In 2012, Julian Philipp Heuss (*1990; trained as an organ builder at Orgelbau Klais in Bonn 2008 -2012) joins the company and is appointed second Managing Director in 2012. 2 years later, his brother Tristan Felix Heuss (*1993; trained as an organ builder at Förster & Nicolaus and OTTO HEUSS 2010 - 2014) also joined the company. Together with their father, they form a good team that continues to drive the company forward. The introduction of touchscreens into organ building, developed at OTTO HEUSS, leads to the company winning the Bavarian State Prize for Special Design and Technical Achievements in Craftsmanship in 2016. The awarding of the Hessian Export Prize 2023 also fills OTTO HEUSS with pride. Stefan O. Heuss retires in 2023. However, he will still be available to advise the company and his sons. At the same time, Tristan F. Heuss becomes the new Managing Director with equal rights. The management of OTTO HEUSS GMBH is now in the hands of the 4th generation. As a creative partner in organ building, OTTO HEUSS GMBH has stood for tradition and progress for over 70 years - everywhere and worldwide.

F. Knittel