Leica IIf: small window under the shutter speed dial

Hi,

I recently obtained a Leica IIf in great condition (my first Leica as well ). While cleaning it, I noticed a hole/crack on the top plate underneath the shutter speed dial. It couldn't be rust since the whole camera looks spotless like it was just taken out of the box. I then searched ebay for some reference photo, looks like there is a window on the top plate covered by a tape of some sort from the factory. I have attached a couple photos, one from my camera where the hole/crack can be found between the narrow space of the coldshoe and the speeddial, one from ebay showing the underneath of the top plate with a window.

My question is:

1. what is purpose of "tape" covered window on the top plate?
2. do i need to repair this, potentially prevent dust and water from getting inside the camera? i would rather avoid doing so since the camera is in such a good working condition that i feel fixing this might make it worse. but that crack is driving me nuts as a camera collector and i think some of you might resonate with me

Is it tape or a contact for the flash sync? Is there something it contacts with when it's together? I just had my IIIf apart a few days ago, the picture below is what it looked like from the other side. Yours looks to be in better condition but I haven't tested the flash with mine. I didn't pay much attention to it when I had it apart, I was focused on changing out the rangefinder beam splitter.

The cutout is for the wiper arm on the flash sync safety switch. Normally there would be a piece of hard insulating material that covers the hole.