Other than on cheap shit there should be a mandrel between the crankshaft and the blade mounting - precisely to stop you bending the crankshaft if the blade hits something. Take the blade off and check to see if there is a mandrel. If so, your worst case scenario should be to change the mandrel. Oh, and the blade.

On cheap shit the crankshaft may have an extended nose. In fact it will need one to put the blade in the right place. You may (may) be able to improve matters by trying to reduce the bend: long hollow lever and/or large hammer. But if your eyesight is like you say it is, it's be better to get someone with good eyesight to do it and preferably someone skilled with a big biffing iron.

I don't know about over there but in the UK you can get a cheap shit rotary mower (about 18 inch blade) for about £100 and a self-propelled one for about £125.   

I have done this before with tree stumps, and once with a very large spanner hiding in the grass!