Sounds like a broken drive coupling to Me here is a link to the part>
If You need instruction on the installation please let Me know I will send them A.S.A.P.
Meant to add asking for model number, slide machine out and remove back panel on Your washer there is a shift selenoid that Whirlpool actualy calls a "WIG-WAG" here is a picture of where it is and another for what it looks like>
and the part itself>
Advance timer to a spin and turn the washer on open the lid and watch this selenoid while someone closes the lid, and then reopens it delaying about 10 seconds after each action.
While watching the selenoid You should see it shift the stamped plate that the selenoid piston is attached too.
You will most likely either see it do nothing or instead of cathing and shifting the sheet metal plate it will skip off the corner.
Tell Me which one You see it doing.
Did the wig wag shift the transmission?
It moves back and fourth any time the motor runs.
Please don't get overwhelmed this should be a fairly easy repair if it ends up being what I believe it to be.
You will need someone else helping You. I would usualy get the customer to operate the lid for Me while watched the wig-wag.
What you will see:
Open the lid and start the washer at the end of a cycle where it trying to spin but leave the lid open. when You get behind the washer it should be running and the wig-wag moving.
There are to plungers off the bottom of the Wig-Wag they look like this>
and the attach to these sheet metal slide the two look like this>
The first lides runs through a rod connected to the brake the lower one connects to the diverter valve lever on the pump.
You wanna be watching the one that operates the brake, once You have found it and know where it is have someone close the lid while You watch, you should see the coil energize pulling the plunger up and move the slide to disengage the brake.
IF it does not do this its one of TWO things either the coil is bad and you need to replace the Wig-Wag or the wires going to this coil have broken under the insulation.
You can easily check for a broken wire.
The copper wire itself will not stretch but the plastic coating will.
Unplug the washer, disconnect one of the wires to the coil in question and hold the end with one hand(hold it at the insulation just past the spade connector) and about a foot away up the same waire grab the wire with the other hand and pull slightly and look for the insulation to stretch (like a slightly stiff rubber band) if it does then where ever it stretches the wire is broken simply cut the wire strip the plastic insulation back enough to splice the two ends back together.
If the wires ok replace the Wig-Wag there is a set screw at the base You can see the hole in the picture above where it screws in (round metal mount in the center on the bottom of the Wig-Wag) remove this set screw and place a flat screw driver between the round mount and the transmission and pry it up and off a stubby shaft that comes out of the transmission, the plungers will slide right out of the Wig-Wag.
Then just reverse removal to put the new one in.
The other thing You may see is the plunger goes up but it clunks and skips over the corner instead of shifting the slide, You will need to replace the plungers and the slides.
If this is the cade let Me know i will explain that repair.