Rugo, with the differing opinions let me add another. If it was me having the issue I would first put the dimmer in the low beam position, access the dimmer switch, remove the high beam wire(s) then temporarily contact them to the low beam side of the dimmer switch. If the high beams come on it's the dimmer switch. If not, your journey isn't over. My personal experience is 90% + of the time it's the dimmer switch. When mine started going bad in the '38 I did as Jerry recommends and got a few more months out of it but eventually had to replace it. The dimmer switch lives in a bad place for an electrical component so I'm surprised they don't fail more often.

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