[68gmsee]

As mentioned above, lubricate everything really well and make sure everything is moving before proceeding to adjustments.

When I've had problems like this I do the following:

Check that all the grommets (rubber inserts -top and bottom) in the holes are in good condition and then disconnect or loosen the links at the column in the engine compartment. Then have an assistant move the shift column lever to make sure both levers move properly.

Next make sure both levers in the transmission are centered in the neutral position and insure the 1st and reverse lever are not interchanged with the 2nd and 3rd (had that happen once).

Make the adjustments on the top levers as mentioned with the drill bit or other. After all is centered and moving correctly, have an assistant go through the gears to insure the rods are not binding against each other. If they are loosen and twist them around so they don't touch.