I've had this skimmer for years and it does need a thin fim of crud to be effective. You are essentially re-breaking-in the skimmer. So wait a few days for it to develop.

The folded paper towel trick is very effective if placed on top of the injector. Just remember to change to towel once every few weeks.

Excessive micro-bubbles can be solved by slipping a piece of filter foam with a slit cut down the middle over the outflow lip. Rotate the foam out every half week or so to prevent nitrate build-up.