Volvo Repair: Car problems, neutral safety switch, battery connections

Question
I have a 96 850 Turbo and am having trouble that I thought would be the starter. There are times that the car will not start, it does not turn over at all, but has full power. At times it may take a couple of seconds before it turns over at other times will not turn at all, but eventually will hours later.  I took it to a Volvo shop and they could find nothing short of it taking a second or two to turn. They did not want to suggest changing the starter when they could not confirm this being the problem. I do find that it will do this after longer trips rather than shorter trips.

Any suggestions?  

Answer
Need to check for voltage at starter when cranking. If no voltage, may be from bad neutral safety switch. Try starting car in neutral and see if this works.
If there is voltage at starter, try tapping it with hammer or mallet. Also listen for starter click, this tells you it is getting power and energizing but just worn out.

And do check all battery connections, both at battery and on engine side, ground and power.