I bought one when I bought my machine but it has never come out of the box.

The best thing I've found for wonky hems on knits is to iron a strip of interfacing in the hem before I sew it.

It has seemed to help me. Also if you can adjust your presser foot pressure so it's a little less than normal that helps too. I'd like to try some water soluble stabilizer sometime for my knit hems too but I haven't figured out where to buy it yet.

:)
Vicki

I just use a big stitch...haven't had any problems so far!

Unfortunately I can't change the pressure of my foot :( I think I will try Kadida's suggestion first and then try the others if the longer stitch option doesn't work out.