Quoted from Atomicboy:
I don't believe this.
Ask Lloyd. He's been pretty honest about it on here in the past. All of the local ops that I talk to have said the same thing too.
I'm not talking about game geometry, which is open to interpretation and taste to an extent, I'm talking about needing to adjust switches, fix broken solder joints, and so on. Initial service calls were quite high until things got worked out.
When Stern became the only manufacturer, one thing they focused on was making sure that the op wouldn't have to deal with a bunch of little issues out of the box, making it easier and theoretically cheaper to route pins. Sega had focused on that issue too with mixed results, as DE machines were known for earning well but breaking down constantly, and thus weren't overly popular with ops.