yes even 1 will shut the axis down. the proper way to test is to use the diode test on ur vom [digital] to see if it beeps indicating a short or a connection. no beep and ur fine. you can by reversing the test leads also read the diode. i find a reading of 540 or so is good reverse the leads and they should go to 600 or so. when u test the diodes if i find one that is say 515 i'll just replace it for gp. you can get 2645n from newark electronics. also be sure to replace the isolation pad even if they look good.