Troubleshooting signals

[BenE]

I have a 71 C-30 that I've been driving for about 21 years. In the last few months the signals will work perfectly one time, the next time, nothing. A few minutes later they work perfectly again. I was wondering if any one else has experienced this. At first I thought it was the switch in the column but now I'm not sure. Can't image the flasher working one time and not the other, then working again. Thought I'd ask here before I started tearing stuff apart.