IT WAS perhaps inevitable that in the last phase of his career, patriarch Mr Deng Xiaoping would be plagued by the same failings that wrecked his mentor and antagonist, Chairman Mao Zedong. Mr Deng's lapses have become apparent in spite of reports from Beijing that the decline of the New Helmsman's health had been arrested by the arrival in the Deng household of a new qigong (''supernatural energy'') guru. The master healer from Er-mei Mountain in Mr Deng's native Sichuan province is credited with having restored some of the 88-year-old's eyesight and hearing. However, like the late Chairman immediately before he slipped into terminal senility, Mr Deng seems obsessed with what cynics call an irrational urge to defend his aberrations. After overseeing the irrevocable transition to a ''socialist market economy'', Mr Deng is spending his last drop of energy on preventing the reversal of the verdict on the June 4, 1989 crackdown, unquestionably the greatest blemish on his record. Observers see a parallel in Chairman Mao's efforts to ensure the ''perpetual correctness'' of his Cultural Revolu-tion. Major political events in China since late 1992, especially personnel changes, could be traced to Mr Deng's ''June 4 syndrome''. Senior Chinese sources said Mr Deng decided last November to dump the Yang Clan - President Mr Yang Shangkun and former strongman General Yang Bai-bing - for fear they might overturn the verdict on the massacre. The Tiananmen obsession accounted for the patriarch sidelining in part such liberal aides as politburo members Mr Qiao Shi and Mr Li Ruihuan. Even if the story that General Yang had engaged in factionalism and that he had chaired a clandestine meeting ''to plot for the post-Deng era'' is true, it was but a secondary factor behind Mr Deng's break with the brothers. Chinese sources said Mr Yang had aroused suspicion by hinting that a strategic revision of the June 4 verdict would boost the CCP's prestige. Shortly before the October 1992 Central Committee plenum, which decided to uphold the leadership's judgement on ousted party chief Zhao Ziyang, Mr Yang had subtly argued for the partial exoneration of his ''crimes''. The president pleaded that Mr Zhao had made contributions to the party through his economic reforms. Earlier, Mr Yang had suggested that it might be better not to press charges against Mr Zhao's former secretary, Mr Bao Tong. More significantly, at a meeting of elders at the Beidaihe seaside retreat last September, Mr Yang had hinted he had the wherewithal to redress the wounds of the 1989 killings. Party veterans present, including National People's Congress Chairman Wan Li, had linked the fall in party prestige to the residual ''June 4 complex'' among the populace. ''It is . . . very difficult to establish the chain of command [that led to the suppression],'' an elder reportedly said. Thereupon, Mr Yang reportedly opined: ''I have documents to show [who made] the decisions in 1989.'' Mr Deng's name was not mentioned. It was assumed, however, that Mr Yang meant he had proof that the troops had acted under orders from the undisputed supremo. ''Deng is afraid that after his rendezvous with Marx, Yang [Shangkun] might pin the blame for June 4 on him in order to make himself acceptable to the cadres and the people,'' a senior source said. ''The patriarch is also fearful of a Yang-Zhao coalition.'' The source added that Mr Yang and Mr Zhao had worked together in Guangdong province in the late 70s, when both played a role in the rehabilitation of three radical intellectuals - Wang Xizhe, Li Zhengtian and Chen Yiyang. Aside from the dynastic politics around the fall of the Yangs, Beijing intellectuals are dismayed by Mr Deng's treatment of two relatively liberal leaders, Mr Li [Ruihuan], who was in charge of ideology and propaganda, and security chief Mr Qiao [Shi]. Both have lost parts of their powerful portfolios. By some circuitous logic, Mr Deng has harboured suspicions about a ''collusion'' between the pair and the Yang Clan. For example, early last year , Mr Yang had suggested that either Mr Li or Mr Qiao would make a good replacement for the lacklustre Mr Jiang Zemin - Mr Deng's choice as party general secretary. And during 1991 and 1992, Mr Li and General Yang - in charge of ideological and cultural matters in the army - had formed a united front against leftist commissars such as Mr Wang Renzhi and Mr Gao Di. Mr Qiao apparently ran foul of Mr Deng because in the spring of 1992 he indirectly criticised Mr Jiang's failure to wage the anti-leftist campaign. The top policeman also hinted he was for a ''limited amnesty'' for June 4-related dissidents. Interpreting attacks against Mr Jiang as an effort to unravel his own succession plans, Mr Deng has shored up the party chief's authority. The irony of these startling developments is that it was Mr Deng who had first undermined the position of his anointed successor. During his tour of southern China 13 months ago, he had criticised Mr Jiang for being timid in reform and for siding with the remnant Maoists. Even more ironic is that it was again Mr Deng who had first tried to undo the damage of June 4 by praising Mr Zhao's contributions to reforms. As the old saying goes, it is all right for a top mandarin to commit arson, but a no-no for a commoner to light his lamp. Even admirers of the Chief Architect of Reform have faulted his narrow-mindedness and lack of tolerance. One of Chairman Mao's last decisions was to rehabilitate in part his rebellious protege, Mr Deng. Mr Deng has never considered reinstating Mr Zhao.