...or perhaps its time to get a new keyboard...?
Have you done typing test online before, it is quite nice, then you can determine where the most mistakes are made while typing (some characters or letters thats left out) and it gives you an overall idea of your typing speed and accuracy - but for self improvement, they have excercises and typing games as well...its just interesting, to test one self....I can send you a link if you like
Very often I'll type a sentence and look up to find all the "A's" missing. I don't know why I have a reluctanct "A." Perhaps it's just a bashful "A." Maybe it's been a naughty "A," and someone aught to spank that "A."