AT THE RISK OF reboiling the blood of one of the city's largest voting blocs -- the people who weren't on the rolls when they went to vote last time -- we remind anybody who feels the slightest bit unregistered of a pending deadline: on Oct. 4 -- a week from Monday -- the registration rolls (such as they are or will be) are to close officially for the Nov. 2 election. And while we'd like to believe that Santa's helpers are alive and well in the elections board, making a list and checking it twice, the lost legions of Sept. 14 had best verify their status before casting their lots and/or ballots anywhere again.

Who's in charge of things is still up in the air, but no one should wait for this matter to be resolved. A postcard, available at public libraries, should be sent in right away. Meanwhile, back at the board, the residents who were dropped but voted challenged ballots last time should be added to the registration lists once their names and addresses are verified -- on the grounds that their perseverance must have meant something.

As a second step in Phase I of a voter-roll cleanup, everyone who votes Nov. 2 should be considered registered. This list could form the basis for a brand new, up-to-date voter registration list for 1983. Then anyone who did not vote could have 11 months to get registered for next year's school board and advisory neighborhood commission elections.

Another suggestion: on Election Day this time, why not have open phone lines between the precincts to assist voters in finding their correct polling places, and to keep coordinated lists of who voted where and why.

These are all actions that can be taken right now -- and should be -- in time for the next election. Beyond the immediate emergency is the bigger job of getting at the causes of this city's series of elections breakdowns, and all indications are that the root causes run deep. They point to major bureaucratic surgery and constant scrutiny, on which we will offer more thoughts in the days ahead.