How To Fix Leaking Wiper Pivot Seals

I just did my wiper seals and used this post for reference, thanks very much. but... Mine didn't go as easy. I had my heater box out because im replacing the leaky heater core as well. So the passenger side was quite easy to get to. the driver side was a bit harder without taking intrument cluster or pedals out. But I ended up getting it done, the only thing is the foam donut got ripped in half and ruined putting it through the cowl. I haven't tested it for leaks without it yet but have a feeling its still going to leak without that damn donut. or is the gasket around the bolts the main seal, and the donut is more for backup?