Quad FM3. Worth repair ?

I have just been gifted a FM3 that's in beautiful condition except it doesn't work. Cosmetically like new , no marks on it at all. It maybe just a simple fix or something more complex. It powers up for a few seconds then blows the onboard fuse. It continually does this. Looking at the boards everything looks original , no blown components , hot spots etc. I would like to get it working again. Any ideas where I should look first. Regards Keith

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