agitator skips/slips

the agitator on my kenmore series 90 washer is skipping/slipping… it will agitate a few times and then skip (not move) a few times, etc… does this mean that my agitator needs to be replaced, or is there something else that can be done??? THANKS!!!

is this the entire agitator or just top portion .if just top it may need dog kit. if entire agitator it may be motor or transmission

I believe it is just the top portion of the aggitator - where can I get the "dog kit", and is it fairly easy to repair?