Wm, welcome to the forum. There are a couple of possibilities for noise. First hold your Drive upside down, centering the pedals and drums. See that your fins are both pointing straight up within a couple of degrees of each other. If not, you could be smacking the hull with one fin prematurely. This is adjustable and not problematic.
You may be experiencing a snapping in and out of the center cog by one of the chain/cables. This center cog is fatter than the others and holds the chain in place during assembly. It will eventually become less noticeable and is not harmful. You can also see this when you hold the Drive upside down and operate the pedals by hand with full strokes.
There is a third possibility -- The aft clew outhaul or fin leading edge may be striking the edge of the hull adjacent to the back of the drivewell. This happens near the end of your stroke on one side or the other as you describe. This would only be noticeable when pedaling and is accompanied by a very small shift in position of the Drive in the well as it rocks back slightly. This represents a minor drivewell alignment issue and is harmless. You can sometimes remedy this by slipping a small tube section or scrap slice of garden hose over the nose of the Drive where it fits against the well as shown here:
The Drive must still be able to rock fore and aft if you sleeve the Drive nose like this.
Hopefully one of these items is the cause of your noise. In any event I wouldn't worry about it too much if everything is functioning well. Lube, inspect and adjust your Drive periodically as per the manual and FAQ section here and enjoy your new PA!
