Kenmore (Whirlpool) washing machine will not agitate

[autumdove]

We have been trying to figure out (for months) what part needs to be replaced on our washing machine.  The initial symptom was that the machine would just stop agitating for a very short period of time (usually a minute or less) during the wash cycle--this could occur one or many times during the wash cycle.  Initally,  it never stopped agitating during the rinse cycles that I know of.  
 
Recently, it would go through the complete wash cycle, never agitating, but would agitate during the rinse cycles.  There has been no problem with spinning, water entering or being pumped from the machine.  The next time I would try to wash clothes it would agitate just fine throughout the wash and rinse cycles.  In fact, last week it worked perfectly load after load.
 
At times, the lack of agitation during the wash cycle would get so bad that I have actually "washed" clothes in the rinse cycle   Last week, it agitated just fine throughout the all cycles, never missing a beat--now suddenly, it will not agitate at all, even in the rinse cycles.
 
Does anyone have a clue?  

We have checked the timer and the control switches with a meter, and they seem to be ok.  We have yet to test the drive motor switch (very hard to get to--have to pull the dryer out of the room in order to get to the washing machine).
 
When it agitates, it isn't sluggish at all--it works with full power.  It is just that either it agitates, or it doesn't...

PS:  An hour after writing this email (but before posting), it is agitating in the wash cycle...

Model 110.92598200

[rickgburton]

When it stops agitating is the motor still running? Next time it stops agitating, push the timer knob up and down with a little force but not enough to break it. See if it starts agitating. I also need your model number.

[autumdove]

When the washing machine isn't agitating, the motor isn't running--there is no sound at all coming from the machine except the occasional clicking noise as the timer runs throuh the cycle (that is with the expection of the motor running as the timer progresses through pumping water out of the tub and spinning).

This is a Kenmore, model #110.92598200.

[rickgburton]

Sounds like it's either the timer or the ETC board. Check to make sure all the connections are on all the way and look for any burn spots on the board.