B40 Brake return spring

[AdrianS]

Is there a brake pedal return spring on the pivot of the rear brake pedal?
My bike hasn't got one and some drawings don't show one. I believe the C15 has a spring. I wondered if the B40 one (if it needs one) is the same?

[AWJDThumper]

The later B40 and C15 models had a concentric spring on the brake lever pivot. The earlier models had a slightly different spring arrangement using a linear spring attached to the lever, I beleive

[AdrianS]

I haven't seen a picture of a linear spring - the brake light switch has a linear spring; I don't know if there would be enough room for another spring. I wonder if the later spring would retro fit to the early models?