The wear on the Guns N Roses pinball around the top kick out is simply from normal usage. Its just like the wear on the gold money note from say Last Action Hero.
The same wear occurs on both machines from where the ball is fired out of the ball lock with high speed behind it.
Also, only some GNR's had factory mylar around the top kick out. I have seen apx a dozen different GNR's over the last 3 years and only 2 had no wear up there and both machines were Home use only and had sold for around $6500 to $7000.
If u can buy a GNR cheap, cause the playfield has wear, it might pay financially to get the playfield repaired n clear coated by someone like Gavin or Timbo, because their work is so good, and u will never know a repair has been made. A friend of mine did exactly that, he bought one with a damaged playfield, payed n got it fixed plus full playfield clear coat, and now, the machine is stunning and he saved apx $2,000.
It may cost arong $6500 or more for a GNR without any wear at all. Many people are chasing one like this, so it might be even more expensive to find a real good one. I will keep my eyes open for a real nice one for you in case one of my mates decides to sell theirs.