94 accord 4 door 4 wheel disc abs

soft brake pedal sometimes. noticed a slightly damp area on the little cylinder in front of ABS module, thinking either this thing or master needs replacement. any ideas of how to confirm which one?

 

replace the master, and calipers. And if you want all new brakes replace rotors and pads. Expensive, but really easy.

 

The master cylinder will leak down the brake booster it is bolted to when it leaks. To be sure if you have no signs of leaks there you could loosen the bolts just enough to pull the master away from the booster and see if brake fluid leaks down.

 

the abs modulator accumulator has a noticeable wetness, does not look recent, i.e. it has dust and particulate imbedded in an area around the accum. could this be signs of a slow leak which would cause intermittant soft pedal issue?