Baby Lock Evolve (Previous Model) (BLE8W) Instruction and Reference Guide - Manual (Page 51)

Balanced tension -
Cover stitch has correct tension when the needle thread sews two rows
of straight stitching on the top side and the chain looper forms a zig zag
on the underside of the fabric.
Needle thread is too loose -
Turn the chain /cover needle thread tension dial to a higher number.
Or turn the chain looper tension dial away from the wide dash at the
words "Cover Stitch", but, staying within the solid gold line. This will
tighten the chain looper thread on the under side of the stitch.
Needle thread is too tight -
For a looser tension turn the chain /cover needle thread tension dial to
a lower number. Make sure that the chain looper tension dial is set at
the solid dash at the words "Cover Stitch".
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49
Cover Stitch - Left Narrow continued
Balanced tension
Needle thread is too loose
Needle thread is too tight
* Tension Adjustment
under side
top side