Do-160

Hi guys,
I've question regarding the Vibration Section of DO-160. The document states that, in addition to the demonstration that the natural frequency of the component has not changed at the end of tests and the tested component would still be able to meet its performance standards, it must shown that no structural failure has occurred. Could anyone tell me if would be considered acceptable to have a cracking propagating during the vibration test but not sufficient to change component's natural frequency nor affect its ability to meet its performance standards ? Additionally, considering that the vibration testing would concentrate the vibration levels that component would be subjected to during its entire life in a 3 hour test period, would be acceptable to replace, during the tests, a deteriorated bushing or seal due the exaggerated effects of the vibration and continue the testing ? I would appreciate your help on this.