  We investigate the contamination of the Sunyaev--Zel'dovich (SZ) effect for
six galaxy clusters, A1689, A1995, A2142, A2163, A2261, and A2390, observed by
the Y. T. Lee Array for Microwave Background Anisotropy during 2007. With the
range of baselines used, we find that the largest effect (of order 13%-50% of
the central SZ flux density) comes from primary anisotropies in the cosmic
microwave background and exceeds the thermal noise in all six cases.
Contamination from discrete radio sources is estimated to be at a level of
(3%-60%) of the central SZ flux density. We use the statistics of these
contaminating sources to estimate and correct the errors in the measured SZ
effects of these clusters.
