On Tue, 4 Jun 2013 20:04:54 -0500, "ChairMan"
wrote:

I assume it's a swivel base?

Seems so to me.

If so, the only thing I can think of is the base(post) on the chair is
improperly mounted.

Yes

Try removing it and turning it around, it should change the center of the
chair and eliminate the tipping.

Count the fasteners. If you get an odd number, add one and divide by
two.

If not, get new chairsg

.... or keep counting