Originally Posted by
TimothyH
Something else is wrong.
Someone needs to check the fit of the post to the seat tube and the operation and fit of the clamp. Grease and paste on the seatpost are secondary issues.
I will check again to make sure the clamp isn't splitting somewhere. It appears to have plenty of room between "tab closure", so it hasn't squeezed itself past the point of mechanically holding, that I can see.