hi
bought a 1976 304 1976 scoutii in original state.
The brake pedal is 'lagging' which will say it won't come fully back to it's neutral position, the po used a spring attached to pedal/dashboard as 'repair'.
Braking is otherwise ok, no leaks, good pedal strength.
What could be the cause of this?
Assuming it's equipped with power brakes and the brake system seems to function normally otherwise...
The most likely issue is that the vacuum booster or the master cylinder has been replaced (previous owner virus!) at some point and the "pushrod" between the booster and mc is not adjusted properly.
That pushrod is adjustable through the incorporation of a very fine pitch thread, it has a wrench flat on the tube and the adjustable ball-shaped tip of it has flats for a wrench also. It does not have to be removed to adjust (though the master cylinder will have to be pulled back to allow access).
The adjustment of that pushrod can be tedious and involve some trial and error. The service manual gives a dimension for setting, but that is based only on the use of replacement parts obtained through an IH dealer back in the day. Aftermarket master cylinders and vacuum boosters vary tremendously in their contact point dimensions, resulting in the issue you describe.
In your case, I'd expect the pushrod to be "short" by approximately 1.5mm, that would be a starting point for fine tuning.
Once the booster pushrod is adjusted, then you go back inside the cab and adjust the link between the pedal and the booster to set a small but distinct amount of freeplay so that the brakes won't be applied continuously. After doing that, then verify the adjustment for the brake light switch.
I just went through this same issue twice in the last month on my own stuff.
