[Histonet] fluorescent microscope problem

[Caroline Bass]

Hello,

I am having a problem with my fluorescent microscope.  It is an old  
NIkon Diaphot 300 inverted.  I don't expect much from this scope, but  
it is usually good enough for a quick evaluation.  However, since it  
is used by numerous people it is constantly being thrown out of  
whack.  Today I have encountered a new problem.  When I switch to  
fluorescence there is a considerable amount of white light coming  
through.  I can even make out the outline of non-fluorescent cells  
when I should only be able to see fluorescence.

Any ideas as to what may be causing this?  I have tried everything I  
can think of.

Thanks,

Caroline