Bangor city councilors will take a closer look at a bond issue that could pave the way for some much-needed repairs at the Bangor Public Library. The building’s 100-year-old copper roof is in such bad shape, officials say it needs to be replaced. So does the roof over a 1950s section of the library.The project is expected to cost about $3 million. Library officials are hoping the city will take out a bond to help pay for it. They pitched the idea to city councilors Monday night. The council is expected to have a first reading of the referendum at the next meeting, March 25th. The bond would go on the ballot in June. Library officials hope to begin construction then, too.