With the gorilla knob there is a fabric/rubber element that wears out and causes intermittent contact. If I remember correctly from when I changed one 'bout 30 years ago it is on or near the steering column under the brake master more or less. Simple to replace but hard to see.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.