Remove a piece using capillary action of a fine point forceps and place the piece on a specimen nail. Check for excess sucrose around the pellet. Remove excess sucrose with a wedge of filter paper. Immediately plunge the nail with the specimen into liquid nitrogen. Swirl the specimen somewhat vigorously and when completely frozen place the specimen in a nunc tube on an aluminum storage cane.
Specimens can remain on the cane in liquid nitrogen for several years.
It is indeed possible there may be excess buffer with the cells. Do this only if the fixed pellet does not hold together on its own. Some fixed cells will form a nice pellet and stay that way. Others tend to go back into suspension. Allow the pellet to sink to the bottom of the tube on its own accord.