Keyboard Fader Knob (top sizes and fit) upgrade?

Hi there,
I want to upgrade the fader knobs on my Arturia Key Lab 88 keyboard. Something my finger tips can more easily settle into.
 
I'm guessing that the tops of 'some' faders that the knobs fit on might be 'generally' universal, but don't know for sure.
I pulled a fader top knob off my Yamaha S-90 and tried it and it fits on the KL88 snugly, but there's a big gap between the bottom of the knob and the deck of the KL88. The body of the Yamaka knob isn't tall enough.
 
KL 88 Metal fader top measurement with knob removed:
1.40 mm thick (0.555 in.)
4 mm deep
6 mm tall
 
So, I think the question comes out to be:
How do I go about finding good fitting knobs and not wasting a lot of money on ones that don't fit?
Let me know what you think?
Thanks!
 

Hi Jim,

No. They're just dumb plastic fader knobs. ( Stressing knobs / tops only ... not the fader itself )
It's just about the difference between a small pointed knob and a knob that cradles the finger tip.
Steve

Thanks Bob.

I've got the local Brick'n'Mortar working on it but if that falls through I'll call Full Compass.

Maybe if you send them a pic of the bottom they can find something close enough

Thanks guys. I've been working with the stock ones and getting used to them.
I think I'll let this little upgrade idea fade away.