Four years after topping out Brooklyn’s office skyline, JEMB Realty pulled off a financial reset at 1 Willoughby Square, bringing in partners and refinancing a tangle of construction-era debt to keep control of the 35-story tower. Only the lower unit carries the Deutsche debt, while the upper floors are debt-free for now. Fitch flagged the layered capital stack as a potential risk, noting remaining EB-5 mezzanine debt and $65 million in convertible loans tied to the joint venture. JEMB said the building is being repositioned with a spec suite program, including prebuilt offices as large as 10,000 square feet. The Willoughby Square tower is 53.5 percent occupied, though the portion tied to the CMBS loan is nearly full, anchored by the city’s Albee Square Montessori Public School, which leases 86,000 square feet.