headlights dont work at all unless lever is held back

Greetings: My 93 Caravan will only give headlight light in high beam and then only if I hold the dimmer lever back against the detent for dimming/ high beam. When I try to click to high, the lights go out as soon as I release the lever.
I have already changed both bulbs.
Any other ideas to start troublesohoot????

Greetings again: I got the lights working again. I pulled the dimmer/turn signal unit out and did what my dear old grandfather said to do for electrical connection faults..... Hosed the thing out with WD40.

If you need a new switch for your Caravan I have one new in the box for $59. I never used it and am trying to sell it.