MILWAUKEE — Tenants at a six-story apartment building near North 23rd Street and West Wisconsin Avenue have been relying on the stairs for more than seven weeks after the building’s only elevator stopped working. For Joel Paplham, 75, who uses a walker and oxygen, getting to his apartment can take about 45 minutes. He said he rests along the way and descends the stairs backward. The effort leaves him exhausted for days, he said, and he is considering moving. The elevator has gone out before, Paplham said, but this outage has lasted longer than any previous one. “I’m fed up,” he said. Other residents also described the stairs as difficult. Tenant Stephen Johnson said he sometimes has to stop around the fourth floor to catch his breath. He said he has contacted the building manager repeatedly about the outage. Berrada Properties, which owns the building, said it contacted the elevator service provider the day after learning of the problem. The company said it is waiting for parts and that delays are affecting the elevator industry more broadly. It said it is trying to speed up the repair, but the delays are outside its control. Milwaukee’s Department of Neighborhood Services said it knows about the outage and has assigned an inspector to investigate. The owner did not provide a repair completion date.