Watch the Dropping the Biscuit online guitar lesson by Andrew Ford from Motown Bass Survival Guide
A very impactful Jamerson signature technique was walking down or up to the major 3rd after beat one. This major 3rd can occur on a down beat or upbeat, but usually stays there for a second for emphasis. It sometimes serves as a pause between the question and answer parts of a phrase. Keyboard master Greg Mathieson told me there was a term Chuck Rainey used for these types of bass fills: "dropping the biscuit", like you have a hot biscuit in your hands that you fumble but finally catch it.
Dropping down to the major 3rd can happen on a syncopated beat or on a down beat. I have 3 examples of the hundreds of ways to use this approach. The first one drops down on the and of beat 1. The second on the and of beat 2. The third example is on beat 2, the downbeat.