how do I remove the bottom drive gear from the agitator ,

icant get the agitator separated there is a flat plastic cap that is pressed in,in the top of the agitator i cant get a screwdriver to pop it out, there are 4 hole that give me access but no luck getting it loose. I Was doing a load of laundry and the agitator came off during the wash. on the bottom is a plastic drive gear, with splines and they appear to be worn enough to replace. I can hear a rattle inside the agitator that sounds like a bolt. the big question, is to me it looks like i will have to damage the drive gear to replace. if i could separate the agitator perhaps i could re install the bolt, and put the drive gear on and then press the agitator over the gear. do i need special tools or am i missing something obvious?