Did not see previous post and not sure how many row planter so this may not apply.

This is from a 7200 standard planter which is much like 7000 although this was on a 6 row.

Is there a sheared bolt on the  blocks that have the ratcheting dogs on them where they are bolted to the shaft ?

Broken ratcheting dogs or springs ? worn sprockets the dogs engage against ?

Sheared drive staples that  the clutch assembly slides on the shaft ?

Frozen and binding chain on seed or insecticide drives.  ?

Some pics of when I re did my shaft.