I would go check where you planted last and see if it was skipping. If the clutch skips the whole planter width would have a missed spot.
Like someone else stated: You may just need to clean the clutch up. Plus the teeth are not real sharp on a new clutch. The corners are not what drive it. The surfaces that lock together should be flat or straight. If they are that way I would just clean it all up.
To change this clutch you have to slide the drive shaft clear out of the wheel assemblies far enought to slide the clutch off. It is a real PIA to do. This is harder on the conservation models. You will need plenty of emery paper to polish everything up to get it apart and back together. If you have it apart than replace both halves and the spring.
That would be part# 15,16,23,and 29. They cost about $160 total. Plus a good half a day to get them installed.
So I would make sure it is skipping before I did that work. Also a loose chain will make it skip too. You need the one in the seed population transmission to be good and tight. I have seen guys just tighten them by hand and have a skipping problem. I always use a big pair of Channel locks to hold the tightener good and tight then tighten the lock screw.