During the spin cycle, the agitator makes a knocking/clicking sounds. Works good other then that.

could be a bad counter balance , u can remove the front panel and run a spin or wash cycle and listen to where its coming from so u don't have to replace all the balancers. on some models theres a heavy ceramic weight at bottom that at times goes bad and throws it off balance, just run it and look where noise is coming from

Needs agitator dogs in agitator.

Possible that the bearings are a suspect, if the machine seems to wobble around. Also if the load is high, does the noise go higher, if so check the suspension, check the mounting and the counter weights.
Please check this link: Wobbling machine

Sounds like brake is partially engaged. There is s kit that may fix that. Part # 12002213.

The clutch assembly works only to release the basket allowing it to spin during the drain and spin cycles. The drain function works only when the spin function works. If the machine also agitates during spin cycles, then the problem is in the transmission assembly not able to release the agitate gear from the agitate spline in the drive shaft.

yes in the spin cycle the agitator and bowl lock if not clothes ball up and machine goes out of balance check the spin coil or electric damper is activated during spin cycle if not replace if blown or open circuit also clutch arm cold be broken have a close look keep me advised

If The washer won't agitate
Check to make sure no clothing got wrapped around the agitator. Check the lid switch, timer, and drive belt, other potential causes, such as a bad transmission or bad agitate/spin solenoid, but they are much more involved.
if the washer won't spin, the lid switch, timer, drive belt, transmission, or agitate/spin solenoid could be the cause here as well. Sometimes if the load is unbalanced or too heavy, the washer won't spin. Take some of the clothes out and try the spin cycle again with a lighter load.

Here are the steps to replace the agitator.
1: Take the fabric softener dispenser off and pry off the agitator lid.
2: Use a socket wrench with an extension bar to remove the stud and seal.
3: Remove the agitator top and bottom.
4: Check the agitator clutch assembly (located in the agitator top) for excessive wear.
5: To replace, just reverse the directions.

Most noises from a washing machine occur during the spin cycle. If you hear loud thumping during the spin, the load of clothes may have become unbalanced. Stop the washer and redistribute the clothes, then re-start it. Repeat these steps if necessary. 
for detailed help with diagrams and step by step instructions click the link http://www.applianceaid.com/washerspinnoise.html

Mine is doing the same thing. I opened it up to see what was happening and it was the drive belt tension arm bumping around. Soon, the belt started slipping during the spin cycle. Now it won't spin and the belt starts to smolder from the friction of the drive motor. If you haven't checked your belt, that's a good place to start.

there should be a rubber washer with the bolt. if it is missing the bolt may back of during agitation. also the threads on the transimision may be stripped. Some Green lock tight found in most hard ware stores should help. the knocking noise is probably due the agitator coming loose.