The deteriorating building at 1520 Sedgwick Ave. in the Bronx is sometimes credited as being the birthplace of hip-hop, due to community room parties held by famed DJ Kool Herc, a one-time resident in the 70s. Since being removed in 2008 from the city’s Mitchell-Lama program, which provides affordable rental and cooperative housing to moderate- and middle-income families, 1520 Sedgwick has been in a steady state of decline, a decline that has been widely attributed to the owner, equity investor Mark Karasick. But the recent sale of the building’s $6.2 million mortgage to a partnership between affordable housing provider Workforce Housing Advisors (WHA) and Winn Residential is expected to improve conditions. The partnership purchased the mortgage from Sovereign Bank at a substantial discount, using a $5.6 million loan from a $750 million municipal fund for the rescue of multifamily buildings from unsupportable debt. WHA is starting foreclosure proceedings against Karasick, after which the tenants, who have been working with the Urban Homesteading Assistance Board, hope to start on the road to cooperative ownership.