I used a 1 3/4 wrench as well, after no amount of pressure with a breaker bar would remove mine and them a breaker bar with an extension (I broke one of my breaker bars in the process) I followed the instruction in the manual and got a large wrench (as opposed to a socket) put the wrench on the nut struck with hammer a few times and bingo.
I have heard many different stories about cranks nuts, from came off on its own to more on my end of things, but if it is stuck the above method with wrench and hammer works well.