Complex sentence: Even though he had long been a CPU (b) member he was frequently in conflict with it, and was twice expelled for "nationalist undertones," he was even forced to undergo a "reeducation" at a factory in 1930-1931.
Split into simpler sentences: Even though he had long been a Communist Party member he was frequently in conflict with the Party. He was expelled twice from the Communist Party, harassed for "nationalist undertones," and taken for "reeducation" at a factory in 1930-1931.