I’d actually be more wary of trying to fix the kettle vs the Amplifier. The on/off switch would be operating on mains voltage, so opportunity for arcing if not fixed right. And proximity of water also might be a worry, should there be anything less than 100% fixed. I’d probably also have binned the kettle.
I kind of regret not getting a professional repair quote for the amplifier. The amp cost about £250 six years ago, and could have been renewed for about the same for the latest version with fancy gimics, so I was assuming professional paid repair would not have been tempting. But since I did not get a quote, I can’t be sure...
Diy repair was effected for circa £35 part cost. And a bit more for sundries like a reel of lead-free solder as I only had leaded, and a fancy little tool for undoing screws around corners, but they’ll go into my toy box and will be used again. I probably spent about an hour diagnosing and 3 hours fixing. A pro’ who knew his way around Yamaha amplifiers would have done it a lot quicker but even so, an hour or two’s labour, plus parts....?