High beam headlight issue on 1960.

Intially the high beams work however after a short time the headlights start to flash on and off and the high beam indicator light on the dash panel also flashes.  Everything else continues to work normally.  When the lights start flashing the light switch heats up.  Checked the grounds and added new ones, bypassed the light switch to see if it was the problem (problem remained)  Any thoughts??  Hotzip  

Heat buildup in a wire or an electrical switch is almost always caused by a poor connection, since electrical current is passing through a conductor that is too small to handle the load.  This poor connection is usually due to corrosion, and can cause enough heat to build in the circuit to melt wire insulation and the plastic wire terminals. You will notice that affected wiring becomes hard as a brick once it cools down.  

Pull your headlight switch from the dash by disconnecting the battery, pulling the headlight knob full out until it detents, pushing the release button on the bottom side of the switch to release the knob, and pulling the knob the rest of the way out.  Unscrew the headlight retainer nut and remove the switch from the instrument cluster, with the wiring harness still attached to it.  Now you can inspec the harness and plug that plugs into the headlight switch.  If any of the wires are hard and shiny, it's because of excessive heat.  Disconnect the plug from the switch using a flat-blade screwdriver to gently pry it off of the switch.  Inspect the sockets of the plug for greenish corrosion, as well as the pins of the switch itself.  My quess is that you might be in for a little electrical work. Cleaning all of the affected electrical connections is a start, but there may be hidden damage to the headlight switch.  My recommendation is to replace the switch (available at NAPA, or your friendly neighborhood auto parts house) and remove each wire end from the electrical plug for proper, wire-brush cleaning.  Give this a go, and I'll be you'll be OK.