Complex sentence: In some instances the theaters operated under the terms of Equity's new stock contract, however, resident theater managers have long felt burdened by what they call Equity's "one production" type of contract used on Broadway.
Split into simpler sentences: In some instances, the theaters operated under the terms of Equity's new stock contract. However, resident theater managers have long felt burdened by what they called Equity's "one production" type of contract used on Broadway.