steve swinehart , jul 06, 2005; 11:55 a.m.
D2-V (variable condenser) head. I bought my D2-V enlarger in 1973. The variable portion of the condenser head is a movable 3rd condenser lens above the two main condensers. The correct positions of the condenser for the film formats are printed on the inside of the door to the variable condenser compartment.

The above makes more sense to me than removal of the top large condenser. you are likely to be missing the third condenser.