Finding a Short in a Wire
One way to find a short, is by buying an auto-reset circuit breaker in the same amperage as the fuse that's blowing. If you can find one that fits in your fuse box, in place of the fuse, that's even better.
If it won't fit in the fuse panel, attach two leads to the breaker, and attach to the contacts in place of the blowing fuse. Have someone activate the circuit continuously if a momentary switch needs held/applied.
Get a quality compass, and start following the wire as the breaker trips and auto-resets. The needle will move each time there is power applied to the circuit. (creating a new magnetic field)
When the needle starts to move less and less with each cycle, you are within a few inches of the problem.
Hope this helps.
Roy