Are any of the Omron internals ALPS compatible?
Coils springs; Diameter of Omron's are bit shorter but can be used in ALPS.
Stems; not compatible.
Click leaves; Omrons' leaves are bit wider. not compatible. Haven't tried ALPS leaves in Omrons.
switching assy; basically same mechanism but not compatible. Clicky Omron has 3 pins. ( Later version has 2 pins but anyway incompatible )
Cases; completely incompatible.
ALPS ( and Monterey ) key caps can be used on Omrons. haven"t tried vv. but maybe OK.