NORWAY END OF AN INSTITUTION INTERRUPTED ONLY BY THE NAZI OCCUPATION, NORWAY'S LABOR PARTY HAD BEEN IN POWER FOR 28 YEARS, LONGER THAN ANY OTHER DEMOCRATIC PARTY IN EUROPE . LAST WEEK IT WAS OUT . AT THE ROOT OF ITS DOWNFALL WAS A LONG-DEVELOPING SCHISM BETWEEN THE PARTY'S MODERATE, PRO-WEST MAJORITY AND ITS FAR-LEFT FRINGE, WHICH DEMANDS NORWAY'S WITHDRAWAL FROM NATO.TWO YEARS AGO, SOME LEFTIST LABORITES BOLTED, FORMED A SPLINTER " SOCIALIST PEOPLE'S PARTY, " AND MANAGED TO WIN TWO PARLIAMENTARY SEATS ON THE 1961 ELECTION . PARTLY AS A RESULT OF THE DEFECTION, PREMIER EINAR GERHARDSEN'S GOVERNMENT LOST ITS MAJORITY IN THE STORTING (PARLIAMENT), FOUND ITSELF DEADLOCKED, 74 SEATS TO 74 SEATS, WITH THE OPPOSITION COALITION . THE BALANCE OF POWER WAS HELD BY TWO SPLINTER LEFTISTS . RELUCTANTLY, GERHARDSEN ACCEPTED THEIR SUPPORT TO STAY IN OFFICE . WHAT BROKE UP THE UNEASY COALITION AND BROUGHT ON NORWAY'S FIRST GOVERNMENT CRISIS IN A GENERATION WAS A TRAGIC SCANDAL IN THE STATE-RUN COAL MINES . IN RECENT YEARS, FOUR DISASTROUS EXPLOSIONS AND SEVERAL LESSER ACCIDENTS HAVE PLAGUED THE MINES, AT A COST OF 74 LIVES . SEVERAL WEEKS AGO, AN INVESTIGATING COMMISSION CHARGED OFFICIAL NEGLIGENCE . LAST WEEK, AFTER FOUR DAYS OF ANGRY DEBATE, THE TWO SPLINTER SOCIALISTS JOINED WITH THE OPPOSITION IN A NO-CONFIDENCE VOTE AGAINST THE GOVERNMENT . ONE OF THE LEFTISTS, FINN GUSTAVSEN, EXPLAINED THAT THE S.P.P . TOPPLED GERHARDSEN BECAUSE " HE HAS NO LONGER ANY CONTACT WITH THE WORKING CLASS . " THERE WAS SPITE INVOLVED, TOO ; GERHARDSEN RECENTLY APPOINTED THAT OLD COMMUNIST TARGET, EX-U.N . SECRETARY-GENERAL TRYGVE LIE, A STAUNCH LABORITE, TO THE POST OF MINISTER OF INDUSTRY . AS THE UNCHALLENGED LEADER OF HIS PARTY FOR TWO DECADES, GERHARDSEN, 66, HAD BECOME A NATIONAL INSTITUTION, WAS SO SCRUPULOUS THAT HE INSISTED ON BUYING HIS OWN POSTAGE STAMPS FOR PERSONAL LETTERS . HE RAN A PART-FREE, LARGELY CONTROLLED ECONOMY, WAS STAUNCHLY PRO-WEST AND LED NORWAY INTO NATO . HIS SUCCESSOR WAS EXPECTED TO BE BLOND, HUSKY CONSERVATIVE FLOOR LEADER JOHN LYNG, 58, ATTORNEY AND BRILLIANT PROSECUTOR OF NORWAY'S NAZI WAR CRIMINALS . CONSERVATIVE LYNG'S FOUR-PARTY COALITION CONSISTS CHIEFLY OF FARMERS, MERCHANTS AND INDUSTRIALISTS, WHOSE ECONOMIC VIEWS ARE LESS STATIST THAN THE LABORITES' ; BUT LYNG WILL HARDLY TRY TO ALTER NORWAY'S DEEPLY INGRAINED WELFARE SOCIETY AND CERTAINLY NOT ITS NATO POLICIES . WITH THE TWO MAVERICK LEFTISTS STILL HOLDING THE BALANCE OF POWER, HE KNOWS THAT HE WILL BE LUCKY TO SURVIVE UNTIL THE NEXT ELECTION IN 1965 .