I ran one for quite a while years ago when they first came out and were actually very popular. If it were me, I'd replace the whole thing, but that's just me. I had to do periodic maintenance to keep the thing spinning but never really replaced it.
When it won't spin any more. Those things last a long time. Not great for a reef tank but fine for FO. I keep the wheel in the sump of my main. Then if I need it for QT I can set it up immediately. Instant cycle in the QT tank.