The musicians of the Chicago Symphony Orchestra have overwhelmingly ratified a new three-year contract which will raise their base salary to $114,000 by 2007, keeping them among the ranks of the highest paid orchestras in the world. The deal also provides retirement incentives for older members of the ensemble, and allows the CSO to reduce the full complement of musicians from 111 to 106 through such attrition. There will be no reduction in the number of musicians on stage for any given concert. The musicians also agreed to pay a higher share of health insurance costs. The agreement comes a week after the musicians had cleaned out their lockers in anticipation of a possible strike.