In the late phase of some complex flare events which produce type IV radio emission, a narrow-band decimetric component with generally a high abundance of spectral fine structures is observed. We identify this late dm continuum as a hypothetical ‘switch-off’ signature of the equivalent two-ribbon flare current system. The quasi-periodic and highly dynamic fiber-burst pattern studied in the February 5, 1986 example is understood as radio evidence for a final reactivation of a cyclic sequence of instabilities in the driven reconnecting current sheet below the rising prominence.