What brand of fuse are you using. I had a fuse blowing on a tom when a magnet was activated. I was using a cheap fuse. Changed to a buss fuse and the problem went away
Pretty sure they're a cheap fuse from jaycar.
Where can I get a Bussmann fuse from?
We have a wide range of Fuses ;
https://www.rtbb.com.au/product/mdl-1-1-4-slow-blow-fuses/