Friends, I’m so stoked — I just pulled off a successful replacement of my Model 12’s power switch, and I didn’t have to open up the unit or do anything remotely technical. If I can do this, you can too.
The trick is to carefully extract the factory switch so that the leads stay connected to it. The switch is glued to the chassis of the mixer, so you have to get under the edges with a spudger or something similar, kind of work at it for a little while to get it loose, then wiggle and wobble it out of place to slowly pull it out.
Once the switch is out, you disconnect the leads (this also required a decent amount of force, but if you pry at the leads enough they’ll let go eventually — just be careful not to lose the leads back through the chassis hole and into the mixer). When you’ve got the old switch fully disconnected, you simply connect the leads to your new switch and pop it back into place.
References: this post outlines the process I followed (the whole thread is useful), and these videos (one, two) were helpful as well, though these guys opened the mixer up and approached it from the inside. Fortunately, all of that disassembly/reassembly is unnecessary if you’re just swapping out the power switch. Here’s the replacement switch I ordered from Mouser.
I have an extra switch here because I ordered 2 in anticipation of screwing up — if anyone wants it, I could probably mail it to you. Rise up, non-technical repair gang!