I'm sure your Kenmore is a fine machine that perhaps only needs a little TLC that a good repair person should be able to do for you. But why not have another machine for a backup. .... one that you can work on yourself. There are many great vintage machines that would fit the bill..... for not much $$. I personally love the singer 15-91 for reasons already mentioned plus they are great machines for FMQ. I tend to lean toward singers because parts are readily available and the experts here are so helpful.
But, you do need to think about what you want to use your machine for. Do you want zig-zag? There are zig-zag attachments for vintage machines. Do you want to FMQ with your machine? The 15-91 allows you to drop the feed dogs. Do you want to do those fancy embroidery patterns that new $$$$$ machines do? Well, I don't know of a vintage machine that will do those. And you might have to rob a bank.
I've found quite a few vintage machines that were reasonably priced.... from $10 to $280. I'd suggest that you try them out. I'm not one to purchase blind.... that's why I buy at estate sales and auctions. I can plug one in and see if the motor works and I figure I can figure out how to get it to sew, thanks to all the QB vintage experts here.
Good luck with your search.