Complex sentence: Many of the original founding team involved in the original show since 1983 left the production, notably Britt Allcroft, director and writer David Mitton, and original composers Mike O'Donnell and Junior Campbell also departed, and became embroiled in a protracted legal dispute with HIT.
Split into simpler sentences: Many of the original founding team involved in the original show since 1983 left the production, notably Britt Allcroft, and director and writer, David Mitton. Original composers Mike O'Donnell and Junior Campbell, also departed, and became embroiled in a protracted legal dispute with HIT.