Ms. Roswell gave voice to Maude Flanders, Helen Lovejoy, Miss Hoover, Mrs. Van Houten, and several other minor characters. She got busy with other projects, such as acting in Switchback with Danny Glover and Dennis Quaid. She and her partner, Hal Rayle, write and voice shows together at Audio R'N'R.
Marcia Mitzman Gaven, the new actress in Springfield, is no stranger to voiceover work. She has voiced characters in Small Soldiers, as well as Red Planet, The Pink Panther and many commercials. On stage, she earned a Tony nomination for her role as Mrs. Walker in Who's Tommy in 1993. She has also given critically acclaimed performances on Broadway in Ragtime and Chess, which gave us the pop hit One Night in Bangkok.
Why did Maggie leave? Rumors from Los Angeles that her departure was the result of a salary dispute. The Simpsons Archive reports that, "Mrs. Roswell originally resigned from the series following failed salary negotiations with Simpsons production company 20th Century Fox Television, during which she was offered a token raise that couldn't cover travel expenses between her Colorado home and Fox's Los Angeles-based recording studios. According to the February 4, 2000 edition of the Los Angeles Times, the amount offered was a mere $150.00 dollars more per episode."
But Maggie returned to give voice to Maude Flanders from beyond the grave in a Halloween episode in 2002. Thus endeth the dispute between The Simpsons and Maggie Roswell.