Let G be a finite abelian p-group, and K a field of characteristic p.
In this paper we show that if F is a free KG module and Psi is an elem
ent of End(KG)(F) is not an isomorphism, then dim(k) Ker Psi greater t
han or equal to \G\/exp(G). This result sheds some light on questions
related to finite, free G-CW complexes as well as having applications
to modular representation theory.