It just blow the fuse straight away as soon as you switch them on. Thought it could be a sticking motor but now not sure because it bows as soon as you touch the switch.
I was thinking the same as you, as it's been stood for some time, the motors can seize up. My rear motor seems to have done this. It might be worth trying another from a breakers or off ebay, shouldn't cost much.
try checking the conections arnt coroded to all the from the wiper stick to the wiper motor, have you lubricated the wiper linkages of the motor to the arm. try removeing the relay as well all long shots but possible.
if you can take the motor out try it without load on it and then try linkages by hand will give you a better idea