have you tried just pushing it gently by the glass itself. once it's set it shouldn't be a problem.
I recently bought a used 1995 Tempra 1.6 i.e. and the left side mirror cannot be ajusted enough so that I can see near my car. The problem is not visible.
Is the mirror actually sat in the correct position? Push the whole housing flat to the side of the car then push back until it locks into place. Should then be able to adjust as required.