DONALD DEVINE, director of the Office of Personnel Management, has unveiled a modified version of the administration's plan to make civil service promotions and layoffs depend more on worker performance. The modifications address many of the objections raised against the initial plan, but there is still reason to proceed cautiously in putting the plan into action.

The concept of tying workers' compensation to performance has few detractors. A majority of the many civil servants who replied to a poll conducted by Washington Post columnist Mike Causey supported the idea--in the abstract. But when asked about putting Mr. Devine's scheme into practice, an overwhelming majority voted "no."

The new plan responds to many of the specific objections raised by those polled. Decisions to lay off workers would be made on the basis of the last three--rather than only the most recent--evaluations; seniority could also be taken into account, and workers would have more opportunity to retreat to lower-level jobs if their current jobs were abolished. Workers could ask for higher-level review of their evaluations, and managers would not have to meet established quotas in rating their workers.

These are all sensible and needed improvements. They don't, however, address civil servants' two primary concerns. One is that the merit pay system already in effect for higher-grade managers and the new performance evaluation system now applied to all workers still aren't working well. The other is the frequently justified belief that their own bosses won't do an honest job of rating them.

More experience, better supervision, more line management involvement and, especially, more adequate funding of performance awards could work the bugs out of the current merit pay and evaluation systems. Weeding out poor managers--including those who unfairly protect favored subordinates--could also alleviate workers' concern that they will be unfairly rated if they don't play along with office politics. But all of this takes time, especially given the very bad atmosphere that continuing layoffs, personnel transfers and top- level hostility have produced in the bureaucracy.

Sen. Ted Stevens, chairman of the civil service subcommittee, has proposed a sensible compromise. His idea is to try out the new performance system on a trial basis with adequate evaluation to determine if it works and how it could be improved. His plan calls for testing to develop rating systems suited to all the many different government occupations and with substantial employee involvement. Mr. Devine doesn't like the idea because he says that having employees under different systems will lead to interagency jealousy. But there is already substantial variatio among occupational pay practices--and even one experimental merit pay system in effect within the Navy. Employees are not likely to complain if they understand that the plan is truly experimental and is being fairly and independently evaluated. On a matter as important as this, surely good business practice would suggest a market trial before moving into full production.