I believe its also worth checking the voltage at the headlight , with the older vehicles there can be a marked drop due to crappy fuse holders, lighting switches ,wiring etc . I have added 2 relays to supply the dip and
main beam circuit and taken the supply to power them direct from the alternator output terminal (via fuse).
My other point is that the Wipac units seem to have a sharp cut off on dip , main is great.....