The blockage/starvation patterns of known instability examples suggest using local demand information-which is precisely what is provided by the widely advocated kanban approach to flow control in manufacturing Systems. Therefore, we have re-analyzed for stability the examples described in the 1990 Kumar-Seidman paper when modified by introducing kanban control. It is found that this does not ensure stability and, in fact, some interesting new instability phenomena arise. Counterintuitively, it is possible that increasing some reserve in a stable system may induce instability.