I think .005 is .0047uF? I have a small disc cap that's showing .005

oops yeah never mind

 

No, it is 5nf (0.005μF)

 

I don't think more will hurt..

The schamatic of a tube amp shows .0047 between 4 5881 tube sockets what I found in the amp was a .005 cap someone has been in here before so maybe that's the reason why things did not see right.

I'm pretty sure the cap is just to prevent oscillation.

 

It will not be an audible difference. A capacitor is generally +/- 10% accuracy.