> I guess we could remove DNA and see what happens ...

If I have a stool with three legs, and remove one leg causing it to fall, can I conclude that removed leg is what made it stand?

You’re making the same mistake as before in reverse: DNA would do nothing without a host cell or chemical signals, either.

> Somehow the machinary is passed down: Do we know of another mechanism besides DNA that is self-perpetuating?

The system as a whole is self-perpetuating, but DNA is not self-perpetuating: without a host cell and without ambient chemical signals, it cannot propagate. That’s in contrast to ribozymes which can be self-catalyzing RNA, ie, truly self-propagating chemicals.

In the RNA world hypothesis, such self-catalyzation was the origin of life; and by the time DNA evolved, it did so within a running biological system and as merely one component of cellular replication.

As a whole the system of chemical signals, DNA, and cellular machinery propagates; but just like our stool example, removing any of the factors causes that to fail.