Humming from MCE600

Answer:

Hi John
The noise could well be due to a blocked venturi or air tap. If the amount
of air available to the pump is restricted the impeller will move forward
and
rub on the front suction plate.
The other issue maybe due to wear and tear depending in the age of the
skimmer. Worn grommets/bushes, foreign object(snails and sand) or other worn
components such as the impeller shaft can all produce vibration. If the pump
is the old type with black grommets you may want to update them with a noise
reduction kit:
http://www.theaquariumsolution.com/sound-reduction-mce600-and-mc500-models

I would like to point you to this FAQ for further reading if I may.

http://www.theaquariumsolution.com/maintaining-mc-and-ap-skimmers-aquabee-pump

You may also find these links helpful when refitting and for identification:

http://www.theaquariumsolution.com/aquabee-pump-impeller-and-grommet-installation

http://www.theaquariumsolution.com/old-or-new-style-pumps-%E2%80%93-which-one-have-you-got

If you find you need any replacement parts or the sound reduction kit these
can be obtained from Neil at spares@theaquariumsolution.com.

I hope this helps.
Regards and best wishes Tony