Originally Posted by miriam

I'm with you on the 403 or the 503 - much easier beast to tame...

The lid to the machine should say how to use the disks. I'm thinking the bottom (or right hand gauge goes on S - can't remember the other but it should say) Put your selectors in the configuration for special then make sure the disk is in right. I'm sure you already did that or looked in the manual... So here is what I would look at after making sure I already read the manual or the lid.
Is the stitch selector moving all the way to the top and locking in it's spots? Those stitch selectors tend to get gummy after a couple weeks of setting around. You have to go easy on oil but you have to have oil. If the oil has dried in the posts or in any little place you have to clean it out and re-oil. While you are in there clean out the zig zag pin - it is next to the cam stack and under the rectangle thingy the readers ride on. Take off the lid - then open up the nose door and push on the needle bar you can see it the zig zag pin thiny move side to side next to the needle bar.... follow that bar with your eyes to the readers - it's under there - when you push on the needle bar you will see it go in and out - it needs cleaning and oiling once in a while - so does the 503 and the 403...