Can anybody help me??? My 89 zillas hubs are loose & the castle nut is torqued to specs!!! My buddys 89 zilla is the same way & completely stock & has never been touched!! Any suggestions on how to fix this??  Inspected hubs & axle & no signs of wear??

The castle nuts on both bikes are bottomed out against the axle!!!!! Im thinking the correct fix is to install a thicker washer to fix it but before I did I wanted to make sure this wasnt a normal thing with these zillas!! Mine is completly non origional & my buddys is a complete virgin one owner with absoutly very little hours on it!

Thank you for your help king!!!