I think my starter motor has finally died. My 850 with 186,000 miles started fine last night. I then heard a few random sounding pinging noises which stopped after about 10 seconds. I drove up the block, shut down the engine. I was unable to start the engine. The starter would not engage. This morning the car started without a problem. I drove around the block, shut the car off and again the car's starter will not engage. If it is the starter how difficult would it be to replace it myself? Thanks for the help.