I had also read of someone else using the same machine experiencing similar difficulties with their zips and, while I am always happy to admit user error/incompetence, I did wonder if maybe something about the zip foot was causing the problem. So, after a prompt from the wise one and a quick google search I did find that my machine can be fitted with an alternative foot like this one
It's much narrower at the back than the standard zip foot supplied with the machine, and as a result it allows me to stitch closer to the zip teeth without the traumas of previous experience.
Armed with a few bits and pieces I decided to road test it and make myself a simple zippy pencil case to store my rotary cutters.
So this little lot
became this wee rotary cutter case
all matchy- matchy with my new travel sewing pouch