We consider Markovian multiserver retrial queues where a blocked customer has two opportunities for abandonment:  at the moment of blocking or at the departure epoch from the orbit. In this queueing system, the number of  customers in the system (servers and buffer) and that in the orbit form a level-dependent quasi-birth-and-death (QBD) process whose stationary distribution is expressed in terms of a sequence of rate matrices. Using a simple perturbation technique and a matrix analytic method, we derive Taylor series expansion for nonzero elements of the rate matrices with respect to the number of customers in the orbit. We also obtain explicit expressions for all the coefficients of the expansion. Furthermore, as a byproduct we derive tail asymptotic formulae for the joint stationary distribution of the number of customers in the system and that in the orbit.