On the Electro 6, percussion in NOT available when activating the organ preset. There is only one preset button - it is either off (default) or on. C/V remains available.
If I'm not mistaken, this emulates the Hammond B3, where the percussion circuit is only available on the upper manual (keybed). So on the E6, the preset button essentially switches you to the lower manual of a B3 when you activate it.