What are the symtoms of a lens that is out of alignment?

[Hamster]

I just cleaned out the fungus on the lens of my GSN and was wondering if I had put it out of alignment. Are there any way to confirm if I had got it right easily?

 

[Windscale]

The first step is to open the lens to f16 and shoot something at infinity. If the 4 corners do not turn out to be sharp then you are in trouble. If all is well, try f11, f8 and f5.6. Your lens should have very sharp corners even at f5.6. If all is still well. Take a flat object at say 10 feet and try the same procedure again. Again, your lens should do well all the way down to f5.6. If you cannot find any fault having done all the above, you must have got it right. Best to do the above tests using a slide film and then examine the results using a 8x loupe.