I just tried Schmetz needles, they work great. They are 80 12 the same size as the Klasse I was tring. These work fine. My stiches look like stiches. With the Klasse my stiches were really tiny, didn't seem to matter what stich length I used. The needle was in correctly. The clunking sound is gone (whee I though my baby was sick).
PS. what's the correct size for the job.

I use Klasse all the time in my Baby Lock and don't have a problem. I use Schmetz in my Juki. Have great results with both.