Hi Dawn, at 40 years of experience your guy has way more experience than me. I can see his point about the wires not touching, but I always make it a point to cover mine up; I guess it's different when you're working on a machine that you love, versus working on a customer's machine when you've got 10 other machines waiting to be done after it. I guess people have different ideas of what's "proper," and I can't really criticize someone with a lot more experience than I have. It might be silly, pointless or excessively anal of me, but when I work on a machine my goal is that if someone looks at the machine in 50 years, after I'm dead, they'll look at it and go "Wow, whoever worked on this machine last did a really good job."
It's not true that you cannot re-wire the light on a 15-91; what's true is that it's a pain in the neck to get the light re-assembled when you're done. Maybe what he meant to say was that it's not cost-effective for him to re-wire that light, as he would spend a lot of billable hours putting it back together, thus it would simply be cheaper for you to buy a replacement light. I've used the type of replacement lights sold by Sew-Classic, they work fine and their styling is close enough to the original machine that they don't stick out, from an aesthetic point of view. So I'd say those are a good buy. (But please don't throw the old light out, sell it on eBay or something! Maybe someone is looking for one of those lights and is willing to re-wire it.)
At some point I should write a foot controller replacement tutorial up on the blog. It is pretty easy to do. I find that with vintage sewing machines, a lot of stuff is pretty easy to do, but it seems impossible unless someone shows you exactly what you need to do and tells you exactly what things you need to buy. I had to learn a lot of things the hard way and I was surprised that clear explanations for a lot of basic stuff doesn't exist on the internet, so I'm trying to fill that gap with the VSSMB blog. I am hoping to save people some of the frustration and wasted money I had to spend.
I can relate to not wanting to learn to solder. I didn't either, but I had to because I've accumulated so many machines that it wouldn't be cost-effective for me to pay someone else to do it. But given a choice I wouldn't do it. I enjoy cleaning and wrenching on the machines but I always look at the soldering part as a chore I have to get through.
In any case, good luck with the new light and the machine! The 15-91 is such a great machine, I'm sure you'll be thrilled when it's all up and running!
- Rain
Vintage Singer Sewing Machine Blog
http://vssmb.blogspot.com/