Malfunctions Malfunctions can occur in a variety of ways. They can be seen on one or both transports. If on one transport, the problem might be in the reproduce amp, the bias oscillator, the bias oscillator or transport power supply, the tape heads, or in wiring. If the problem is on both transports, it might be in the ac power supply, the failsafe amplifier, record amplifiers, the monitor amplifier, the clock or DAIR circuits.