I have two FF in my '03 Classic and the only problem I ever had was with the front one. It motor would not shut off with the cover completly closed. I took the fan all apart and found that the pin that holds the crank to the shaft, that lifts or closes the cover, has fallen out. I put it back in and it works just great.
I love these fans and would not hesitate to replace the current with new Fantastic Fans, if the need ever arrives.
Mac from PEI
Prince Edward Island
'03 Classic 30'
'10 Toyota CrewMax