Does it have ceramic powerball (40 pound or more to replace). Do the eddy sensors work correctly (trough one is fiddly to get right, but can usually be repaired if not reliable).
High wear areas would probably be rocket kick out, slot machine, piano, under diverter (where diverter drops it) and left inlane (under ball drop). Bumpers usually have Mylar around them.
Play game with glass off to test the toys (gumball machine, mini playfield magnets)
So - I had a Wh2o and all was good. The lure of owning a TZ set in and i ended up getting one, then realising i didnt have enough room. So i ended up selling the Wh2o and keeping TZ.
Worst move i had ever made.
Where Wh2o was nice and flowing, I found TZ very stop start. It rapidly became apparently that i really didnt get on with it. Should have kept Wh2o.
The motto of the story is - I hope you like it Wasnt the machine for me tho . Buy it because you like it and get on with it, not because others say it's good
Shame too, TZ is quite possibly the bet pinball machine out there, although, I went the other way to Paul and traded mine for a WH2O. Don't regret it - loving the WH2O!