  Agreement with the measured electronic widths of the $\psi(4040)$,
$\psi(4415)$, and $\Upsilon (11019)$ resonances is shown to be reached if two
effects are taken into account: a flattening of the confining potential at
large distances and a total screening of the gluon-exchange interaction at
$r\ga 1.2$ fm. The leptonic widths of the unobserved $\Upsilon(7S)$ and
$\psi(5S)$ resonances: $\Gamma_{e^+e^-}(\Upsilon (7S))=0.11$ keV and
$\Gamma(\psi(5S))\approx 0.54$ keV are predicted.
