Those clear connectors in your picture are just a push in quick connect. Kind of crappy if you ask me but they do the job. If you suspect there is a bad connection in there somewhere you can eliminate them entirely with wire nuts. If you tug on a wire and it comes right out of the connector the connector is no good. I don't believe they are isolated connections but do a continuity test just to make sure if you decide to eliminate them.
I should add don't go tugging on wires with it powered up.