So back to the original question here a short check list:

1. reflecton the reason why would you want to change NB?

2. is your certificate still valid?
3. when is the next surveillance audit due?
4. have you any major non-conformity still open/pendig?

5. have you any non-confrmity still pending open?

6. for what service do you want to change your NB? ISO 13485? CE marking?
7. What about to bundling other certifications with the new NB?

8. Find a serious NB
9. Safety and Quality come first
regards