Gerry, Are you wired by NM cable or through a conduit?
With a flashlight look in the switch box to see where the wires enter the box and report back on:
Type of insulation on each wire: cloth or plastic
Color of wires
Where wires enter the box are they individual
or do they enter as a pair with an outer plastic sheath?
With a flashlight look in the switch box to see where the wires enter the box and report back on:
Type of insulation on each wire: cloth or plastic
Color of wires
Where wires enter the box are they individual
or do they enter as a pair with an outer plastic sheath?