I have been tuning a number of older Steinway Grands Models A, D, O, L. I have yet to figured out how to get the strings to tune (move) or to settle the string on pitch. I have tried a slow steady pull or a number of short jerks. Every time the string will jump from 20 flat to 20 cents sharp. When you try to drop it down, it goes 20 cents flat. So far no bro#en St@in@s. I hate to even think of that result. How do other tuners handle grands like this. A Baldwin I did was similar. I do not want to even get into tuning Steinway uprights

"older Steinway Grands Models A, D, O, L. I have yet to figured out how to get the strings to tune (move) or to settle the string on pitch. I have tried a slow steady pull or a number of short jerks. Every time the string will jump from 20 flat to 20 cents sharp. When you try to drop it down, it goes 20 cents flat."

Is this all the strings, or just the trichord agraffe section? If that is the only area,you more than likely have rendering problems over the felt that is just proximal to the agraffes. The fix is to apply CLP (Protek) to the strings where they cross the felt. It will not migrate to the tuinig pins,and it will allow the strings to be set.
Regards,

Correct. Some pianos just "creak or creep" when tuning.

Just don't "douse" it with CLP... You don't want any falling down into the action or especially onto the hammers.

"I have yet to figured out how to get the strings to tune (move) or to settle the string on pitch." dherbon

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Some of the rendering skill is practice. Stubborn, jumpy pin blocks don't respond to much except intelligent overshoot and practiced manipulation.