  We explore modifications to the current scenario for the slow neutron capture
process in asymptotic giant branch (AGB) stars to account for the Pb deficiency
observed in post-AGB stars of low metallicity ([Fe/H] ~ -1.2) and low initial
mass (~ 1 - 1.5 Msun) in the Large and Small Magellanic Clouds. We calculated
the stellar evolution and nucleosynthesis for a 1.3 Msun star with [Fe/H]=-1.3
and tested different amounts and distributions of protons leading to the
production of the main neutron source within the 13C-pocket and proton
ingestion scenarios. No s-process models can fully reproduce the abundance
patterns observed in the post-AGB stars. When the Pb production is lowered the
abundances of the elements between Eu and Pb, such as Er, Yb, W, and Hf, are
also lowered to below those observed. Neutron-capture processes with neutron
densities intermediate between the s and the rapid neutron-capture processes
may provide a solution to this problem and be a common occurrence in low-mass,
low-metallicity AGB stars.
