NMR troubleshooting no signal

[adidalol]

Let's say i have a problem with my NMR machine. I only know that that there is no spectrum, one think that is given to my information is that the tuning/matching (wobb) is working and signal is received. What where your first thoughs on what is wrong, what to do in the next?

My thoughs: 

Magnetic field drift: If the magnetic field drifts away from the resonance frequency of the sample, the NMR signal may be lost. This can happen due to changes in temperature or other environmental factors.

Shimming problems: Shimming is the process of optimizing the homogeneity of the magnetic field. If the shims are not properly adjusted, it can cause signal loss or distortion.

Probe failure: If the NMR probe is damaged or malfunctioning, it can result in signal loss or poor spectral quality.

Software issues: Problems with the NMR software, such as bugs or compatibility issues, can prevent the acquisition or processing of NMR data.

Radio frequency interference: If there is interference from other radio frequency sources in the vicinity, it can cause signal loss or distortion.

I thought lastly about that we want to use a different nuclei, and we have to retune the equipment.