Not sure on your game, but slam tilt is usually mounted on the door.

I'm not familiar with Sega's at all, but a blown fuse would go out and stay out. I don't think it would cause a reset. Not sure. I would send a message to LTG for advice.

Fuse blown isnt an issue for resets maybe a loose fuse holder, ive seen that be a problem before, but first thing on resets if it doesnt say slam on your dmd would be checking mpu 5vdc curcuit is holding steady/low, it should be a touch over 5v. If you cant do that you could at least re-seat all the ribbon cables in the backbox and see if it changes the situation.

Yes.

You should at this point reflow solder on any header pins on the boards where re-seating ribbon cables took place just to be sure. There may be a hairline crack or loose solder joint on the ribbon cable plugs causing continuity loss. Most likely the one inbetween the two big boards, do both of those.

Sure man i own one too as of a few weeks ago, so if you run into something feel free to pm me for some info ill help you run through some stuff or whatever, cross check with my game, that sortof thing.

This could also be of help

http://pinwiki.com/wiki/index.php?title=Data_East/Sega

and within that, reset issue:
http://pinwiki.com/wiki/index.php?title=Data_East/Sega#Power_Supply_Issues

Could be that the watchdog sets in. Check http://www.sternpinball.com/upload/downloads/sb112.pdf and follow the instructions on the service bulletin. Something you should do anyway. Might solv your random reset problem.

It won't solv you random VUK problem though. That sounds like a bad diod or something, check if the VUK triggers when you push another switch in the matrix. If, for example, the VUK triggers when you trigger one of the slingshots. Things are never completely random