Using “off brand” bobbins
I love my Janome sewing machines and I make every effort to treat them right.
What “may” save you a few pennies right now may end up costing you hundreds of dollars in future repairs.
I don’t use “off brands” bobbins or presser feet for any of my machines and you shouldn’t for yours.
Does the tension seem to constantly be “off”? Is your machine making bird nests? It’s probably your bobbin.
I’ve included an example of what you’ll get when you buy a bag off off brand bobbins - they’re garbage. I ordered these to show you what you will get (and yes I’ve sent them back). One has a hole filled with plastic, others are broken or misshaped. The most concerning though is the rough bits of plastic on the inside and outside of the bobbins, this will cause damage to your machines and mess up your thread.
Your sewing machine is an investment and if you treat it right it’ll give you 10 or more years, perhaps even decades of use.