My apologies! I was wrong!
I realised as I was making a bag while waiting for tea to cook, that I was thinking about the Brother machine I use at home, which is different! Whoops, sorry Chris! I DO usually change the stitch length to 3.0 on the MARX Brothers - particularly if the machine is having trouble making headway on the handles. My comment on longer stitches for thicker materials stands, though probably 4.0 would be too big in most situations.
Mea culpa, *calls for the sack cloth and ashes..*