- Don't replace that sideart. Always keep original anything, unless it absolutely can't be salvaged. 20+ years from now, it will make a big difference in value, and it's nice to have the character and wear of original anything IMO, over shiny new repro stuff. Only replace as an absolute last option.
- There are multiple options for Tubes, depending on how technical you want to get. The easiest option is to contact brzezicki. He makes a simple kit that can drop in, and give you Tubes, and bypasses all of the ROMs, making the board more reliable. There is also another guy here (I forget who) who has a 'kit' that is basically just a replacement for the one ROM that holds the tubes code (as it's only one ROM that changes).
- The original Tempest spinner knobs didn't have Atari logos (as far as I'm aware, unless there was something different in Canada). My guess is you probably have one of the later spinner knobs that was used on Blasteroids and I think other games, assuming the rest of the spinner is the same. (Post a pic of the underside.)
- Marquees are tricky for Tempest. I'm not aware of anyone that makes a really good repro. Some here may tell you Phoenix Arcade, but theirs has issues, as I've documented in the thread below. My personal suggestion would be to find another original replacement, as replacing the overlay is a massive pain anyway, and there should be a fair number of originals still around.
http://forums.arcade-museum.com/showthread.php?t=386506&page=4
Aside from that, I repair everything vector, and especially Tempest. If you have any other questions, feel free to post here, or PM me anytime.