I've spent a fair amount of time fixing up my Laser War, so I wanted to document some of my findings in a central location.
1) Have a dead Rev 1 or Rev 2 MPU? Convert a Rev 3 Data East MPU board to be Laser War compatible as fully documented in the following thread: http://pinside.com/pinball/forum/topic/laser-war-not-fully-booting
2) Have significant ball bounce on transition from return frame to flipper in the inlanes? Pick up a set of High Speed return lane guides from Cliffy as documented in the following thread: http://pinside.com/pinball/forum/topic/laser-war-flipper-return-frame-replacements-cliffys-frames-for-hs#post-1390827
3) Want an amazing light show experience? Install LEDs throughout the game. I used bulbs from pinballbulbs.com, including flashers. WELL worth the investment of time and money--Laser War has a top-notch light show and the LEDs give it some extra pop. I also went with red/blue/warm white GI in the red/blue/yellow team areas--adds nice ambiance in my opinion. See a nice example of Laser War with LEDs here: http://pinballsoul.com/laser-war-pinball-gameplay-video/
4) Having ball bounce out from base shots? Add felt pads to the metal stoppers on the red, yellow and blue bases. On my machine I was also seeing significant bounce out of good shots to the yellow base. I added a blue rubber pad (http://www.pinballlife.com/index.php?p=product&id=689) *adjacent* to the metal stopper, attached to the metal lane guide that feeds to the WAR rollovers. What I found was that many shots came through, struck the metal lane (instead of feeding to the saucer) and bounced out. With the blue pad, hard shots tend to deaden out and fall into the saucer. I might at some point attempt to cut a 45 degree angle into the blue pad to further encourage the ball to deflect into the saucer.
5) *Some* folks recommend replacing the stock "walnut cracking" flippers. I found that I actually enjoy mine--just make sure that the game is at 6.5 degrees slope or steeper.
6) Need a new ramp? MAD amusements has them for $45: http://mad-amusements.com/product.php?id_product=321
7) Display out? Pick up a XP-WMS10877 set from xpin...Wonderful product (I went with red): http://xpinpinball.com/products/displays/XP-WMS10877