What happens if ...?

....the pulses are wrong? Sensitivity is decreased and signal can be missing. For instance, if the 1H pulse length/power is miscalibrated in a 13C spectrum with 1H decoupling, sensitivity is attenuated because we can obtain a 13C without decoupling (there is no 1H decoupling). ....the probe has not properly tuned/matched? Sensitivity is decreased and signal can be missing. For instance, if the 1H channel is not properly matched/tuned in a 13C spectrum with 1H decoupling, sensitivity is attenuated because we can obtain a 13C without decoupling (there is no 1H decoupling), even in the case of pulse length/power should be correct. ....the shims are wrong? Signal lineshape is distorted and this causes loss of sensitivity and resolution.