1985 Honda VT 500 C Shadow brake light not working

SOURCE: Where is the thermostat located on a 1985 honda shadow vt 500?

I've got the service manual if you want it?

SOURCE: Honda magna tail light not functioning properly

Did you just replace the bulb with the LED? If so, you probably got the wrong bulb. Make sure it is a 2 circuit bulb like an 1157 dual filament.

SOURCE: Rear brake light will not come on when rear brake is applied

If your brake lights are not coming when pressing the foot brake this means that there is something wrong with the switch..Have a closer look near the brake lever and you will see a spring attached to it which in turn is connected to the brake switch..Try to pull it down and if you see your brake lights working then you only need to adjust the spring setting..Else try to make a manual close connection and if it goes on then replace the switch..

SOURCE: How do I remove the seat from an 85 Honda Shadow 500

Mine bolted in from the back of the rack. Remove the rear cover.

SOURCE: Front brake too stiff on 1984 Honda Shadow VT500C Shadow

You should have disc brakes??? They are not adjustable.
It is common for a caliper piston to freeze up or become corroded and bind up so it will not move freely.