My previous post including information on brother ribber alignment suggested some things to test when ribbed fabrics are troublesome. I happen to own two 910 machines. The recent 2 posts on using generated mazes addressed developing the repeat for use in a punchcard model machine, but for the sake of speed I knit my samples on the electronic. In attempting to knit DBJ swatches relating the motif, I encountered random dropped stitches on the main bed, as may be seen in the last swatch pictured.
My Brother 850 ribber rarely gets used. I prefer to knit DBJ on my Passap, which can accept PC downloads. With the 850 in place, all things I could think of were checked: ribber was balanced, at the correct height, brother ribber brackets and not studio ones in place by mistake, correct ribber sinker plate for model, all parts oiled, good condition needle retainer bar on main bed, no needles that vaguely look like they need to be replaced, familiar yarn in use. Knitting fabric single bed with ribber engaged and weights gives expected results with no problems, while dbj, no matter the setting, begins to drop stitches randomly or in groups on main bed (tried different amounts of weight as well). I did not try to use a fine knit bar, since the yarn in use had not required it in the past. After spending way too much time rechecking everything yet again, I moved the knitting close to color changer, away from the center of the machine, and the darn thing knit perfectly. Back to center, same problem as before. I cannot see any noticeable difference in spacing between beds or gate pegs in the center, assume there may be an issue with some bowing, and briefly I got things to knit properly by lifting the middle of the bed up a bit with a support. A second shot at it with support failed. I even changed needles in the middle of the main bed. A few instances of mis patterning were probably due to static, relieved by using a vaporizer in the knitting room for a while. I took the ribber out of sheer stubbornness, removed it, slapped it on my second 910, using the same needle retainer bar on the main bed, and knit the same pattern with only one dropped stitch and one mis patterning error, knitting as fast as possible. I am admittedly flummoxed. The only thing I did not try was to use the troublesome 910 on a different knitting table. Some days are meant for walks on the beach and eating chocolate instead of knitting ;-).