Richard Vars

Hello - new to the forum. If this has been asked and answered I apologize in advance. Please point me in the direction. I have a 2009 duramax with the manual extend/fold, defrost, lighted, etc. tow mirrors. The driver side mirror arm only locks into 2 positions, straight out or in so much all I can see is the side of my truck. I try to push it out so it will stay in a good angle which it will do but if I hit a bump or shut the door it springs back to one of the unusable positions. Any idea if I can adjust where these lock in? I can't even move the glass mirror enough to compensate for it. Appreciate any help you can offer.