Complex sentence: Eventually, however, Dot found it increasingly difficult to compete with the larger Motorcycle Factories and the demise of their main engine supplier, Villiers, and the increasing number of foreign imports spelled the end of large scale production.
Split into simpler sentences: Eventually, however, Dot found it increasingly difficult to compete with the larger Motorcycle Factories. Further, the demise of their main engine supplier, Villiers, and the increasing number of foreign imports spelled the end of large scale production.