Complex sentence: However, it has not been on the air continuously ever since nor always under the'WSM' callsign (the current WSM-FM began in 1968, an acquisition from another broadcaster); hence other FM stations have a longer history of continuous operation.
Split into simpler sentences: However, it has not been on the air continuously ever since nor always under the'WSM' callsign. The current incarnation of WSM-FM began in 1968, an acquisition from another broadcaster; other FM stations have a longer history of continuous operation.