Tito passed away in 1980 at the age of 88, and his influence had been waning for at least a decade before his death. His final significant power move occurred in 1972 when he dismissed the Croatian leadership. However, it's worth noting that he also dismissed the Serbian leadership, seemingly in an effort to maintain a semblance of parity. The constitutional changes in 1974 paved the way for Yugoslavia's eventual disintegration, and it became a question of whether the republic leaderships could come to any agreements.
As for concerns about Serb domination in Yugoslavia, it's important to consider that each political reform in Yugoslavia since the end of World War II had weakened the federal administration while strengthening the republic administrations. By the time the last constitution was established in 1974, each republic had its own president, government with various ministries, police, secret police, and some form of military forces (territorial defense). On the federal level, each of these institutions had become a mere shadow of what they were just 20 years earlier. To pass any decision at the federal level, a majority vote was required and Serbia had one vote just like everybody else (that will change once Milosevic got control over two autonomous provinces in Serbia but that happened only in 1989-1990).
In the case of Serbia proper, by 1974, two autonomous provinces, Vojvodina and Kosovo, had gained so much autonomy that they had voting power on the federal level. These two regions of Serbia already possessed legislative autonomy, meaning they could pass laws for their own territories without consulting the rest of Serbia. Consequently, there was a central part of Serbia that found itself somewhat beholden to these two autonomous provinces.