Process-morpheme stems

[Tuggy, D.]

     Do any of you funknetters know of a case of a root or stem which
     consists of a process morpheme?  Zero stems have occasionally been
     posited (and I'd be interested in any good examples of those you
     have), but I don't know of any stems consisting of say a tone pattern
     or (more likely) tone shift, an umlaut or ablaut, a reduplication,
     palatalization, etc. It seems like they should be a predicted kind of
     limiting case, though there are good reasons for them to be pretty
     rare.  Any examples?

     --David Tuggy