How to seal a gasket lid onto a bucket

Here I am with my trusty rubber mallet, pounding the heck out of the edges of this gasket lid.  (These are the cheap lids, around $1.75 each.  Most food storage has these lids.)

We tried to push the lids down with our hands, but that was worthless.  Go buy a rubber mallet, it is so much easier.

You really have to wale on it, and hit it quite violently to get the edges to pop down.

Note:  Only hit the edges, don't hit it in the middle or it will crack.