Yep, my mum’s machine will not do plastic bobbins, not anyway not know how!

I’m sure I’m winding or loading the bobbins wrong, but it’s a Bernina and I’ve been using a Brother for the past 12ish years, so I’m not used to the front-loading bobbins (even though it’s what I learned on in high school). It’s a beautiful old machine, recently serviced, so I’m pretty sure it’s me😂