Tunze skimmer stopped skimming

[VO3434]

I have a 29 gal biocube with a tunze skimmer, the skimmer stopped skimming and I have no idea why. Trying to set it up again but no luck. Any ideas?:8fish:

 

[Letsgotothezoo]

Does the pump working ? May be there is a clog in the pump. Take out the pump, clean it and rinse it in the vinegar

 

[VO3434]

I will try that, thanks