Thanks John for the suggestions.

Arcadeboneyard has a good selection, but shipping was a little pricey.  I ended up getting an 8-ohm "guitar speaker" from mcmelectronics.com.  Seems to work OK.

Haven't tried scrubbing my TMNT marquee any more, I'm afraid the yellowing is likely permanent, not something I can clean off.  thisoldgame.com is supposedly going to have artwork available soon so maybe I'll go that route.

Not sure how much more I'll invest in the cabinet, my kids have already played through the game multiple times, and now that I've tamed the nicotine/smoke smell with an odor eater, I feel like I can now detect a bit of a urine smell... ick.

I had a very similar problem on my dkjr and dk pcbs.  Fixed both by replacing the 10125s on the video board.  They're available on ebay.

I picked up a TMNT 4-player to follow along with John's restore. ;)

It's missing a speaker, which I didn't think was any big but I'm having a hard time finding something that isn't overkill.  I'm assuming I need a 6.5" circular speaker.  Manual indicates 8ohm/6W or 4ohm/12W will work.  I'm finding a lot of smaller speakers, like 4", but the 6.5" stuff tends to be more $30+ 50W speakers.

So... anyone know of a good source for speakers?  Surely this shouldn't cost more than $10?

Another not so technical question that isn't necessarily TMNT specific:

Are magic erasers safe to use on marquee art?  My TMNT must have sat in a smoke filled bar for 30 years because it's *drenched* in a nasty coating of smoke and nicotine.  I used a magic eraser on the control panel and it whitened right up.  I used it a little on the side art and did damage.  I anticipated that and the side art is pretty chewed up so it's not a huge , but was surprised how much ink came off.  But the marquee placard looks really nice *except* its yellowed all to hell and *reeks*.  I cleaned it with simple green which helped the smell but the yellowing remained.  I really want to take a magic eraser to it hoping that it'll clean up like the control panel, but if it's going to wreck the artwork I guess I'd like to try something else.