1960 Thunderbirds have a separate in-line fuse holder tucked up, beside the headlight switch. (Don't ask me why.) Click on the diagram below for a printable, more legible size:
This fuse feeds the Brake Switch on your Master Cylinder. If you have power there, the fuse is good.
I tell everyone I can to extend the fuse wires so you can relocate the fuse holder to a more convenient location.
Your steering column is fed from two different directions because the flashers interrupt the brake lights. Follow the wiring diagram from the Steering Column connections:
The Key Switch feeds the Stop (pressure) Switch. The 'switched side' continues to the Steering Column (green wire).
The Key Switch also feeds the Steering Column through a fuse on the Headlight Switch and onto the Flasher Unit (blue wire to the Steering Column).
If you replaced the turn signal plate, you should be very familiar with the bullet connectors at the base of your steering column. All power and light wires can be checked for power right there, with the Key Switch on.
A dim bulb usually means you have a grounding issue. This is common with old cars. I run a separate stranded copper ground wire from my battery to the trunk area, branching off
for the dash, power windows, seat motors, convertible top motor, trunk light, fuel tank ground and tail light and license plate housings. This wire can be bare and bolted to the floor in various places. I guarantee you won't have a ground problem again. - Dave