I'd clean the outside surfaces only. The theory of a condensing lens system is to bring rays of light parallel to one another ... the reflector of a flashlight ("torch" to those of you who speak "U.K.") is an example of a condensing system. Whatever dust, etc., is on the interior surfaces will not have a major effect on the image - mainly, it will decrease the amount of light passing through. No focusing, per se, is done by the condenser array.
The empirical test for a condensing lens system is to try it without the focusing lens -- simply remove the enlarging lens and turn that puppy on. Ideally, you should see the image of the bulb filament projected onto the plane of focus - and centered in that field. If it is, you will have the most EVEN illumination across the field that is possible.
Simply put, I'd advise against tearing things apart.