Models
1995 Ford F-250, F-350 using 10-4007 or 10-2690.
Problem
Low or long pedal action.
Cause
According to Ford technical service bulletin TSB 96-25-19, the master cylinder should be changed to a unit with a larger bore size.
Solution
Before changing the unit, perform the following checks:
With the engine off and all vacuum depleted from the booster, check the pedal action. It must be high and hard. If it is not, either the master cylinder is bypassing or something else in the system is causing the low pedal (check ABS valve if so equipped, all flexible brake hoses, or for air in 
system). Note that the booster cannot cause a dropping pedal — it either works or the pedal will be hard.
For 10-4007 (without cruise), upgrade to 10-2827. For 10-2690 (with cruise), upgrade to 10-2828.
Courtesy of CARDONE ProTech.
