Signal lights Intermittent

I have 1985 BMW 735i, the signal lights stop flashing when turned on after various lengths of time. Sometimes they work, sometimes will work for a few seconds, or sometimes never turn on. Can someone please help trying to get the car roadworthy. Previous owner neglected this fine auto.

it is an 1986 not an 85

checked bulbs they seemed ok. so replaced flasher and that did the job. Thanks to all you have helped me.