Protein skimmer problems

[Stat]

Just a quick line before work here guys and gals. I have having problems with my coralife super skimmer 220 I can get it to make small bubble into the neck but it will not make the foam I am use to with my older red Sea skimmer. I do get Green gunk stuck to the inside of of the neck but it doesnt seem to make any large bubbles or Foam that rise out into the collection cup and any dry foam. I can make it produce some Green water if I adjust up the water coloum so that the small bubbles are at the top of the neck. But I am really looking to make some dry foam.

Any help would be appreciated.