Problem karlsuss: loss of wafer vac after load

[franklin at snf.stanford.edu]

After loading my wafer, and then the machine tries to do WEC  it gives the message loss of wafer vac along with a hissing noise.  If I ignore this message I just get really crappy litho lines.  I did notice that if as you are sliding the wafer tray into the machine during load and press down on it a little after finishing the load, the machine has no trouble getting a proper vac.  This isn't a good way to run the machine but it might help you figure out what the problem might be.
nate