Complex sentence: Lynn Newcomb Jr. took over the operation when his father passed on, and ran the ski area for all but a two-year period, when it was sold to two San Gabriel Valley businessmen in the 1990s.
Split into simpler sentences: Lynn Newcomb Jr. took over the operation when his father passed on. Lynn Jr. ran the ski area for all but a two-year period, when it was sold to two San Gabriel Valley businessmen in the 1990s.