Check for playfield wear around the horseshoe and between the slings. Backglasses are always mint on this title for some reason.
Horseshoe area is always the first area that wears on these. Play the game and make sure it works.
Check the boards - look for corrosion on the MPU and "hack jobs" on the Power Board
This looks to be one of the better SI's I've seen (from pictures). Could be worth around the $2500 mark. If you snag it for $1700 or less - Then I would not hesitate.