Abstract: Apparatus for detecting the presence of contamination films and foreign material on the conducting fingers of a circuit board. The apparatus includes a guide block assembly (11) designed to receive and momentarily hold a circuit board (100) and a spring biased hold down bar (25) for securely holding the circuit board in the guide block assembly. The apparatus further includes apparatus (23, 31) for use in positioning a plurality of probe assemblies (33) to simultaneously engage a pair of electrodes (330) with each one of the circuit board conducting fingers (101). A controller (43) enables switch apparatus (42) to selectively connect each pair of electrodes with electrical resistance measuring apparatus (50) to measure the resistance of any contamination film and foreign material appearing on a circuit board conducting finger between the electrodes of each electrode pair.