It sews great and I had it on the M. I thought it may have something to do with the tension although the main tension dial in on the front.
I don't have the manual but I found a downloadable one for a different model that is almost the same, except for this lever. The one in the manual has the flat plate like the one mentioned by QuiltingVagabond.
Mine is 1954. I called Husqvarna and gave them the serial number and they look it up for you. Pretty cool.
Thank you for the help. I will experiment with it. I have no extra feet with this one. Just one bobbin. Thats ok. I don't need the extra feet. Maybe a couple more bobbins.