Problem with turn signal

Hey guys,
i just bought a 2000 GT M5 this weekend . The car looks really sharp and is overall in good condition. One problem i recognized is that the left turn signal is not working 100%. Sometimes it's working normal and the other time it's not flashing but it indicats a steady signal. Some solutions to solve that problem? The right turn signal is working proper.

Mods so far: SLP LM Catback, K&W adjustable Coilovers
Pics are coming soon, just have to clean her.

Thanks in adance.

Martin