2 Questions on tube replacement

I am using an Icon Audio PS-1 MKii phono stage.

My record suddenly stopped making any sound at all. I noticed that one of the three output tubes was not firing, so I am going to try replacing it.

The phono stage takes 3 ECC83/12AX7 tubes.

My two questions are:

1 — Can I substitute ECC803 for the ECC83s?; and

2 — Do I need to switch out all three or only replace all one at a time?

Thanks in advance.