proform 750

Those are emulsion bleeds. Your plates only have 3? Most of the Pro Form blocks I've seen have 4 per Venturi.

If you want to run the emulsion they have you can run that. IIRC, those blocks have a .028 hole in them. I usually start with a .028 hole in the 1 and 3 hole from the top and block 2 and 4. But it depends on how much air bleed you have and jet sizes etc.