Hi Angela,
I have a Toyota 901 and you are right to start with the lace carriage on the left.
I have had similar problems and found that when sliding the lace off the extension rail it wasn't seating properly on the needlebed.
Check that it is not raised at the front but that the front hooks on to the needlebed. Try a 'dry run' with no knitting to check that the needles move correctly; only apply slight downward pressure as you move the lace carriage.
Also make sure you have a slightly looser tension than you would use for stocking stitch.
Sue
January 2010