The Singer Model 15s and other Singer models, the Japanese 15 clones and others, all have one design feature that causes me no ends of trouble.
The bobbin loads vertically from the left end. Quilters that do FMQ love the vertical bobbin because the thread path is said to be straighter and less problematic. I don't know about this as I haven't learned to FMQ yet.
The problem is, the bobbin cover or slide plate covers an opening too small for me to get my hand in and R&R the bobbin case easily.
These machines were designed back in the 1800s when the only people that sewed were women. And for the most part women had and still do have smaller hands than men. So since my hands are bigger it's difficult for me to stick my fingers all the way down to the bobbin case, open the latch with two fingers and without dropping it, withdraw it from it's pocket.
Some machines are harder than others too. The slide open cases are just a wee bit better than those with hinged bobbin covers, but not much.
The only machines that are harder for me to change bobbin in than the Singers are the old White made machines with the little lever at the bottom of the bobbin case latch. It, like the hand wheel moves opposite the intuitive way you'd think it should.
I like to use the machines to make at least one project after I clean, oil, and adjust them. But it's getting to the point that I'm avoiding the clones and other machines with vertical end loading bobbins when I go to sew something. I'd much rather use machines with the drop in bobbins like the Singer 66, 99, and others, and my favorite Japanese clone the Sewmor 404. It's basically a clone of the Singer 201-3.
So, heresy or not?