 Complete the following phrase:  The rest of 1989 was characterised by gearbox and various other problems, including a disqualification at the Canadian Grand Prix and a black-flagged incident at the Portuguese Grand Prix for reversing in the pit lane, which resulted in a ban for the next race in Spain. However, Mansell finished fourth in the Championship with the help of a second win for Ferrari at the tight and twisty Hungaroring for the 