Vertex Omega 150 - not skimming as usual

[kamloops_reefer]

I've had this skimmer for just over a year now, and have used it off and on 3 times now between moves. This time, the skimmer just doesn't seem to 'dry skim' very well. Rather than fine bubbles at the top, they are quite large but for the most part the bubble level is just below/above the connection of the skimmer cup during normal operation. Every morning I get some skim, although not quite as thick as I'm used it - its watered down quite a bit. If I adjust it to skim more with the pump output pipe / angular discharge it over skims eventually. I've had past problems (and vertex replaced) with the needle wheel in the past, has anyone had similar problems and offer any solutions? I've already taken the motor apart and rinsed clean - went from over skimming to under skimming. perhaps there is some finicky step I've overlooked.