that "one" small hole is a aligning hole to put and seal driver in, so when replacing the rear main seal, the seal driver sits perfect on the crank, then can hammer on the driver, so that the seal will go in straight, and when the driver hits the block, thats where u stop, and should be good........when u are doing this, dont use any DIY plate to put the seal in, use a honda seal driver, even every honda is different, so high recommended use a honda rear main seal driver for s2000, make sure u put some high temp. grease on the seal before u put it in too, that will help the seal to be easier to go in.......and try not to damage the seal, even a little cut will cause oil leak........

 

On an 04 with tranny and engine completely out of a car Turbolane and I had the same problem. This was at the Ultralite shop and Brian said most of the ones he's done have stuck at about the same spot. He uses a wooden wedge to separate, we just used a wooden pry bar and worked it around the edges.

Upon reassembly it stuck at the same spot. It took 3 of us jiggling and changing angles for it to pop back on.