Hi Craig,
Just saw this post come up among F51 error codes (as it will show previously posted and answered questions ) and wanted to add some info I have regarding this exact issue you may or may not already have, no harm in posting either way.
The F51 typically indicates a failed "RPS" has been detecected...but it can be the result of other issues...just for future reference and if anyone has not come accross this before.
The scenario you describe is usually associated with a item stuck under the tub or a loose stator or a faulty "RPS" device or connection at the "RPS"...but I don't know if you checked that yet or if you know how, thus the error F51.
**The repair tip below is directly from Whirlpool**
F51 is usually associated with the rotor and stator/RPS assembly and quiet often it is initiated due to a loose rotor or bad RPS...I'd start by checking the bolt.
There is a repair tip regarding this which suggest checking the wires to the RPS and then the rotor, while insuring the center bolt is really tight via applying some "lock tight".
I actually see a lot of these and most times it's a loose rotor bolt, that is where I always start my diagnosis. Here's an exert from my files directly from Whirlpool...

You may want to check the rotor, I've seen the center bolt become extremely loose, thus causing the F51 error, this is where and what to look for shown below...

...but either way that should help out with the repairs and good luck.
Regards,
Macmarkus :)
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