slapshot5279

I have been having problems starting for about a week.I have heard clicking noises from the starter area. This problem has become worse over time and now will not start at all. I was able to jump start it a few times but not anymore. Now all I hear is one loud click and the whole panel goes dead until I "reset" it by disconnecting the battery. It will then light up the panel and glow plugs but will not start, only to click one time again and go dead. I have replaced the battery, checked cables and ground, checked main fuses. I was thinking probably solenoid/starter but not sure how to diagnose the problem. Any help would be appreciated!!