Volvo Repair: sometimes have trouble starting the car, battery cables, battery connection

Question
I sometimes have trouble starting my car sometimes it starts and sometimes it doesn't.  I go to start it and it will not start then i wait for an hour and then it starts.  I checked the battery connection and the battery it self, it does not seem to be either of these. Do you have any suggetions to what the problem might be?
740 sle 4 door v6 1987

Answer
HI Mario..
   HMMMMM..
 My first reaction is to say...dirty electrical connections....almost 90% of this kind of problems is electrical related..
Be CERTAIN that your battery and other hot wires to support systems is CLEAN...also...could be your starter.
Next time it dosen't start...hold key in start position for 15 seconds...feel battery cables...the hot one is the prob....or...locate the starter and hit it hard with a hammer or other heavy object....don't go crazy...see if this works
..this will tell you that the starter has a problem