Sounds like the Multi-function switch is misbehaving.
Usually, the pins on the connector side, not the switch itself, are the culprit.
There are two connectors attached to the switch and the problem lies in the smaller of the two.
Remove the switch assy. from the steering column and then disconnect the connector.
Check the pins as, over time, they will spread out to the point that they no longer touch the spade connector at the switch side.
Using a very small screwdriver, you can usually press them together so they fit tighter and make contact once again.
**The multi-function switch is the turn signal stick**
If you do a search, I believe there are some pictures and a step by step guide also.

Gary