Technical Tips on fitting Holley check valve

I have just bought a pair of these umbrella check valves for my 390cfm 4160 Holley, as my one needed replacing. The old valve came apart where it came out the hole in the accelerator pump. Any tips on fitting new ones without damaging them, as I only have two and they came form the States!!
Vaseline I presume...?

 

That & pull slooooow.
dave

 

Using just needle nosed pliers (carefully!!)?

 

Yes, slight push with index finger [on which ever hand is holding the bowl] while pulling with pliers or just fingers if they strong, doesn't take much..Be sure the hole has a slight beveled entry, no hole edge burr..