"attract mode" is when the game has no players - the credit button has not been pressed and the game is not "playing". If you press the flipper button and the fuse blows, then there's something VERY strange going on.
If you press the credit button, and player 1 is on ball 1 and you then press the LEFT flipper - does anything happen ? I assume that at this point you press the RIGHT flipper and it blows the fuse ?