To improve the reliability of the punch when used on card, a modification has been made to it. The aim of the alteration is to increase the punch pin drive, and it simply involves unsoldering one end of resistor R129. [this applies to the TTL versions of the 4070 only; if you have a DTL board you're on your own :-) ]
This mod has already been made to the CUCPS punch. (Actually, we have two punches; the one used for punching has a CUCPS label on top; it's also easy enough to tell if you look at the PCB which has been modified...)
CUCPS should have a copy of the 4070 service manual if you want further details on this.