Hi Poppy,
It sounds as though the patterning mechanism has stiffened up.
The first thing to check is that all the cams and levers on the underside of the carriage are working as they stiffen up with oil and fluff. You should clean off the old oil with a cloth moistened with surgical spirit and apply fresh oil on another cloth. If it is very dirty, you can use a small paint brush with surgical spirit to clean it off. Then check the parts are working by pushing buttons and turning switches while watching to see what is happening.
Sometimes the patterning plates under the needles stick together and pushing the carriage, set to pattern, back and forth over the needles will loosen up the selection. I recently bought a Brother 864 and tried freeing them by moving the carriage but the end needles would not select. I dripped some machine oil into the needle slots and left it for a couple of days. When I tried it again it had loosened up and the needles selected properly.
Hope this helps correct the problem.
Sue, January 2014
