nana1234,
The older Kenmores are generally very good machines. Their model numbers will start with three numbers then a dash then more numbers. Like this: 117-812 or 158-13470 or 358-######. I don't recognize the 2142 number.
The Touch & Sew is a Singer machine, not a Kenmore and probably will have plastic gears inside. Some of their owners love them, some hate them so much they've nic named them Touch & Throws. I do not know as I've never used / owned / or worked on one.
If you are looking for an older Singer ZZ I'd suggest a 200, 300, 400, or 500 series. Many of them are all metal inside and will last till the end of the world.
Most any Kenmore with a 158 - ##### will be good as well.
Joe