A motion before the Cambridge City council asking the city to withhold payment of its MTA deficit until services prove, failed passage yesterday. 
 Councillor John D. Lynch produced the measure because of what called the Authority's "public be  attitude. He charged that MTA officials showed  concern for sheltering bus riders in Harvard Square or for changing locations some inconvenient bus stops in North Cambridge.  Councillor Lynch resides in  Cambridge. He said this attitude could be rectified  if the officials "had half a brain do it."  It is time, he opined, for the MTA to give Cambridge citizens a break.  The 4-4 vote failed to give the motion  majority.  MTA regulations require  cities to defray a  of its deficit.  All Councillors, including those who favored the motion, seemed concede this, and off-handedly acknowledge that the City Manager would have  the bill even if the measure had carried.