There are two common failure modes with vibrators. THe contacts get hot and stick, or the contacts just get eaten away. Both are caused by too many hours of operation, or a bad buffer cap.
I suggest you turn the radio on, if no buzzing, use the handle of a medium screw driver and give the vibrator a couple of hard raps, if no buzzing, extract and pitch. They either work, or they don't work.
I suggest you go here to get a new solid state
replacement. THese fully replicate the wave form from a mechanical vibrator, including dead time. Not too expensive but they work very well. Usual disclaimer, have simply used a few with no call backs.