Complex sentence: By 1942, sales of the engines had not been entirely successful, having sold only about 2500 units, leading the Whizzer operation to be sold to Dietrich Kohlsatt and Martin Goldman.
Split into simpler sentences: By 1942, sales of the engines had not been entirely successful, having sold only about 2500 units. The Whizzer operation was then sold to Dietrich Kohlsatt and Martin Goldman.