I own a Whirlpool GHW9100LQ front loading washer. Here's my problem. On normal cycle, the washer won't spin the load properly. Even though I have selected high speed spin, the washer will only rotate for about 30 seconds at 100rpm on one side then the other. It seems to balance the load properly and drains properly but after a few seconds it starts vibrating a lot, stops spinning and continue with the cycle. A technician came over and though it wasn't draining properly. He replaced a pressure valve for 140$ but it didn't solve the problem. I removed the front panel and inspected the shocks and cement plates and everything seems OK. I've also ran the diagnostic provided by the manufacturer and everything was fine. The washer level is OK and I've also checked that it didn't rock in any direction. When empty, it spins perfectly getting to the ~1000rpm speed without any vibration at all but when a normal size load is in, it's like hell is breaking loose. What should I check now? Any hints would be greatly appreciated. Phil

Thanks for the advice,

Yesterday, I have removed the top and back panels to inspect the washer. Everything seems OK. The main pulley isn't warped and the bearing on the back shell also looks good.
Strangely, the washer didn't vibrate violently as it use to. I'm suspecting that the drum may have made contact with the back panel.

BUT, there's still an issue. On the normal cycle, the washer won't spin. I though the washer was acting that way because of the vibration but it isn't the case. After the rinse cycle it starts to spin to stays at about 100-300 rpm for about a minute or so. Then the cycle completes. Afterward, I have selected the drain/spin cycle and it did spin properly (high rpm for about 3-5 minutes).

So it doesn't sound like it's a mechanical problem. What would be the cause of a washer that won't spin correctly only when the normal cycle is selected?