C3 ('68) A/C, HTR, DEICE cable

[Pete G.]

I have the guage bezel and right hand lower dash off my '68 for clock and radio repair so decide to check on health of the heater box. On the A/C, HTR and DEICE cable (right hand thumb wheel), the action works well from A/C to HTR, but does not activate the deice setting (switch from floor and lower dash to upper dash) when moving the thumb wheel from HTR to DEICE. It seems that the cable is hanging up in the cable sheathing when the thumb wheel is moved from HTR to DEICE setting.

Do these cables need period lubricating, or is there other issues here?

Thanks!