TZ is one of the best. Pure pinball at it's finest. I agree about the clock. if it hasn't been rebuilt it will need it.
The trough proximity sensor can also be a problamatic issue but it's an easy fix...i soldered the wires directly to avoid the connectors and never had a problem again.
Some of the GI strings are overloaded and can overheat when the bulbs get old...changing to led's or new bulbs can solves this issue. Because of this TZ usually has burnt connectors.
I feel TZ is one of the most complex games with the ball traveling under the playfield in subways and a six ball multi, magnets and plenty of game modes, 4 flippers with great cross shots both left and right.
TZ was a machine before it's time.