Probably the gearbox as it is the only part you haven't mentioned.
Check to see if the belt is broken? They are not easy to work on as the case has to come off. Remove the console, undo the case screws.
The machine is designed with an automatic water level sensor that even in a deep setting allows at the most 5 inches of water. The reason for this has to do with government regulations regarding energy efficiency.
While you could check intake hoses, this does not change the facts.
This would seem to possibly limiit the wash load. I would refer to the manual for any insight about that. My suggestion is to place the laundry evenly distributed just below the top holes of the basket.. For me to say it had 3.5 cubic feet capacity is of little value because who measures laundry by cubic feet. I hope the suggestion is of some help.
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The F5 error code indicates that the Central Control Unit (main machine control board) detects a temperature sensor resistance that is out of the normal range. The F5 error is normally caused by a failed NTC temperature sensor.
May be a bad door switch. Washers usually let you open the machine (top load) while in wash, but not for rinse and spin because of the high speed. If the door switch is bad, it may think the door is always open and therefore wont go past the wash cycle.
use google for that. all washers made have 2 manuals and spec sheet and sales brochure.
google is your friend , do it or ask any kid for help, (school classes)
They do wobble until the spin sorts them out. Half fill the drum with small light items like socks, underwear and tee-shirts and run a cycle. It you put a number of large items, they are often hard to balance out.
The water value screen could be clogged or have debris or any other foreign objects that are stuck in it. The water value screen may have to be replaced on your washing machine.