Does altering the Speed Switch make a difference in the agitate/spin speed at all? (I realize that you would have to judge this by sound when it is spinning as it most probably will stop spinning when you lift the lid. You could perhaps view the agitate speed difference between gentle and regular, not sure about this though as it does vary between manufacturers as to whether you can or not).
Here is an image of the wiring diagram for your washer.
(click to enlarge for better viewing)
If it is slow for both agitate and spin perhaps the Speed Switch is stuck in the slow position (contact wise) even though you have selected the regular position.
If you have a DMM (Digital Multimeter) you could use its' Ohmmeter function to prove whether the switch is electrically OK or not.
The following is in the area shown by the Green arrow
With the power disconnected from the washer you would have to dis-assemble the control panel to gain access to the rear of the Speed Switch.
Here is a link to an exploded view of the parts of the Control panel which may help you to dis-assemble it. (Use the mouse scroll button to enlarge or reduce the size of the image in the page)
Once you have access to the switch you need to disconnect the wiring plug from the switch. With the Speed Switch in the gentle/slow position connect the Ohmmeter test leads across terminals 31 & 34 of the switch and there should be continuity. Then operate the switch to the regular/fast position and the Ohmmeter should register an o/c reading. If it still shows a reading then the switch is faulty.
If it shows o/c then connect the Ohmmeter across the 32 & 34 terminals and ensure that there is now continuity between them as the switch is in the Regular position.
The following is in the area shown by the Red arrow, which is inside the motor
If the Speed Switch tests OK the problem could lie in the motor with the Centrifugal switch that switches the motor windings between Regular and Slow in conjunction with the Speed Switch setting and the actual speed of the motor. If both the agitate and spin speeds are slow then this switch could be the problem. Unfortunately it would require either replacing the motor or getting a motor repair service to fix it.