[Jukebox-list] Seeburg DS160 tube?

[Jim Algar]

I have a Seeburg DS160 with the "scans twice but won't select" problem. 
I've gone through the troubleshooting guide tests, with the result 
(according to the guide) that it's either the pulse amplifier tube 
(12AX7) or the pulse amplifier itself. Thought I'd start easily (and 
less expensive) with the tube. I see all kinds of 12AX7 tubes on eBay.

My questions:

1.) are any and all 12AX7 tubes the same? I notice that some of them 
carry additional numbers/letters after the 12AX7 as sort of 
"suffixes"...do they mean anything or can they be ignored, as long as 
the tube is listed as a 12AX7?

2.) Any brands and/or countries of origin to be sought out or, 
conversely, avoided?