probably not a bulb problem
An intermittant surging problem would seem not to be logically caused by a brake light bulb, because hitting the brake would either disengage the CC or not disengage it. As I understand the device, the amp cannot reingage after one hits the brakes.
It's probably more likely to be a bad circuit in some other portion of the amp.
Semibodacious Transmogrifications a Specialty
1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)
"Time flies like and arrow, yet fruit flies like a banana"