Something, I know not what, got on the handle knob of my Revros and now the knob is deteriorating and sticky. From what I see per the parts diagram, you have to replace the entire handle, not just the knob. I don’t see an attachment screw. Anyone know if the knob can be replaced without replacing the entire handle?

Brian, may not be anything you did - sometimes bad rubber formulation just separates - I had that recently on a Wheeler screwdriver bit-holder.  

That's a tough knob swap, because I doubt the handle was made for it, possibly riveted with bushings.   Also pretty sure this reel was made by Tica.  

 

You can find a big range of hex-shaft handles on Amazon.  (you can also search reel handle knob)

If you want to try the knob route, first take it apart. see what's there and measure - here's Daiwa shaft dimensions 

@BrianMDTX I bought this reel for a buddy last year and its a great reel for the money but I am pretty sure that the handle is one piece and the knob is riveted like @bulldog1935 said. I've seen this happen on reels over the years and what I've done is ordered knob sleeves from Amazon.  They are cheap and easy to put on.