Odd indicator behaviour

[ArtistsRifles]

For a while now our Ex had been showing odd behaviour when using the indicators. Usually just on the left turn but occasionally on right when the switch is moved the relay goes into warp drive suggesting a blown bulb - but no indicator on that side of the vehicle works.
However - push the switch back to main beam position and the indicator starts working normally. Sometimes just pulling the lever forwards to flash the headlamps will do the same thing. But not always.
I've replaced the indicator switch assemble - it's made no difference. Any one care to hazard an opinion/ guess as to what is wrong??

 

[SB98UKexplorer]

the stalk contacts need cleaning, its all copper tracks inside that build up muck easily, 10min job of undoing it and cleaning it out