The procedure for setting up the 97 card reader is in the service manual, available on the MoHPC CD-ROM.
Basically, there are 3 contacts -- card inserted (to turn on the motor), card-at-head (to start reading/writing) and corner-clipped. The leaf contact has 5 screws through it, The 2 at the edge hold the contact in place (and should be tight), the other 3 each adjust one of the contacts.
IIRC the procedure is to connect a continuity tester (Ohmmeter, etc) across the PCB connections for each contact (with the reader fully assembled), screw in the adjusting screw until the contact just closes, then back off a specified amount (something like 1/8 of a turn)
That's fine for the 97, where you can get to the reader and the adjusting screws with it assembled. It's not good for the 67, where the contacts are on the keyboard PCB, and you can't get to the adjusting screws with it in place. I've found a good basic setting for the 67 (and 65 which is much the same) is to screw in the adjusting screw until the contact finger just starts to lift.
If necessary, push a card through by hand (or with the motor, disconnected from the PCB, running from a bench supply) and check the contacts switch correctly. YOu can find the connections on the keyboard - logic PCB pins, see my HP67 notes for the pinout (or get the HPCC schematic :-))
Before adjusting anything, clean the contacts _and the pads on the PCB_. Clean them with propan-2-ol and with a pencil eraser if necessary. I had a 97 reader that would not set up properly which turned out to be due to dirty contacts.