In this paper an algorithm is provided to approximate the tandem behaviour of a finite-capacity G/M/l queueing system, each with a generally distributed inter-arrival time, a single markovian processor, the first-come-first-served queueing discipline, and an instantaneous Beroulli feedback mechanism. In a queueing system with such a feedback mechanism, a fraction of the departing units will instantly merge with the incoming arrival units to be reprocessed again. Furthermore, approximation results are compared with those from a simulation algorithm.