The mystery deepens.
A guitar with that serial number should have the triangular "DuoJet-like" control cover. They changed the shape to rectangular when the added the phase switch to allow better access. A phase switch and triangular cover would be very strange indeed.
A guitar with that serial number should have the triangular "DuoJet-like" control cover. They changed the shape to rectangular when the added the phase switch to allow better access. A phase switch and triangular cover would be very strange indeed.