Assuming its the correct value and assuming the fuse only blows when the radar is turned on and the fuse has worked ok before this thing statrted - then its probably best to go back to JRC.
I would not fancy trying any surgery on the machine itself.
Perhaps worth checking with handbook that the fuse is the correct value
Does it blow when radar is in standby or when you start the 'head'?
If the latter then it is the head, probably the bearing in the rotating arm.
If the former then probably in the main box.