question about 1/4 seam

Ladies- I know you are all experienced quilters.  I have been working (very slowly) on a wonky log cabin quilt.  I'm having a really hard time getting my 2 and 1/2 strips, and other strips to sew with 1/4 seams.  The seams are crooked, and the feed dogs don't seem to be grabbing the fabric.  Is there a way to raise and lower the feed dogs on a Janomme 1600?  (will have to check on line for the instructions)  Should I cut 12 1/2 in squares of muslin for a foundation backing?
Thanks for your input.
Sara in Fla.