Is that front chuck nut made of nylon/plastic?
also if the machine came with a slot in the screw were the needle bar goes i am sure these would sell even quicker also a top rca mod would be nice as the holes on the clipcord area are huge n sloppy-which makes for power flow problems, maybe these are some mods your shop could offer as a selling point,also a back machine cover would be cool.
These are just some suggestions and what is holding me back from buying one.