5-Thread Stitch: 2-Thread chain stitch and 3-Thread overlock

Top is with left needle position (and loose
green needle thread). Bottom is the
right needle overlock position. 

Next stitch is the 5-Thread Stitch: It has 2-threads for the chainstitch and 3-threads for the overlock.

The overlock stitches can be narrow (Right needle) or wide (Left needle). Strangely, when I use the narrow (more distance between the chainstitch and the overlock stitches),  the stitches for the overlock look good. However, when I move the needle over to the left side, the Green needle thread is loose. Same tension settings . . .

Tried increasing the tension for the needle thread to 5 (rest are 4), but not much of a change.

Packing away for today; will have to try rethreading if it doesn't work!