You have guessed the usual issue but far as I know there is no adjustment unless the switch has completely fallen apart in which case it will not work period.
Is there an Emergency Brake indicator on the dash? Here is why I ask
On my Workhorse (Chey engine) the parking brake pedal switch has the jacks sensor wire hooked to it. The dash indicator is hooked to a tap off the jacks cable. SO if the dash indicator is ON.. then the Jack sensor lead MUST be grounded
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times