Well if it helps (and you cannot source a GTA one) I've repaired one of mine by using an R25 item as a donor. Although the switch front and connector are different, I found that the internal rocker and contacts to be the same. Pop the switch front off and swap over the innards (also replace bulb at same time if blown, this is also the same as the R25). However, R25 switches are not as common as they used to be now!