[A/S] built in blender (maybe)

["tradewinds83801" <corliss2@xxxxxxxxxxxxxx>]

Hi all, we're contemplating buying a 1976 Argosy 26' trailer and 
there's a "plate" between the sink and stove with two knobs on it.  
The bottom knob is broken and the top knob has a thing underneath 
that looks like something would attach on top of it.  I'm guessing 
maybe a blender.  (the seller doesn't know)  Does anyone know what 
this would be, if the unit is repairable, where we would get a 
replacement, possible cost, etc., etc.?  We're in the N.W. USA.  
Thank you for any help you have.