The Writers Guild of America and CBS reached agreement on a new contract yesterday, following several days of marathon sessions at the bargaining table.The new deal is a three-year and one-month contract, which includes an immediate pay increase of 3 1/2%. Also included are 3% and 3 1/2% boosts in the second and third year. This replaces a three-year deal that expired March 1. CBS presented the guild with its final proposal yesterday morning following a session that had started on Wednesday. Guild negotiators met in the afternoon to accept the package. Covered under the deal are 275 network and local radio and television newswriters, editors, desk assistants and researchers. Also covered are promotion writers and graphic artists. Employees concerned are located at CBS O&O facilities in L.A., New York, D.C. and Chicago. Members covered in the deal will vote on the pact at meetings in each of the affected cities March 8-9. WGA negotiators, according to a statement, were able to resist attempts by the company to erode guild jurisdiction. Moreover, the guild said it successfully obtained an agreement on steps to take to help alleviate workload and harassment problems. Guild negotiators were seeking health benefits for temporary workers, which they got. “These have been long, tough and often frustrating negotiations in which our members fought to maintain the professionalism in which they take pride,” WGA chief negotiator Mona Mangan said in a statement. “We are pleased we were able to fight back attempts to take away important past gains. A CBS representative could not be reached. The guild maintains it defeated attempts by the web to have certain non-represented workers do newswriting, which would have resulted in layoffs at the radio division.