Did you try cleaning the fans? A good brush and some compressed air in the right spots usually can make fans run much better, and some oil.
That external fan is a neat idea, computer fans these days are quite nice and would work perfectly with that setup. there are special low noise and vibration models that also move lots of air.
Also I recently noticed that my enlarger power supply was causing a slight vibration on the table whenever I turned on the enlarger lamp. You could feel it when I hit the footswitch, the metal box of the power supply would pop a bit. So now I have everything off my enlarger table besides the enlarger, the power supply is on a separate box and the timer is wall mounted with foot switch.
I replaced the old and worn fan in my 45S color head with this variable speed model, was easy to wire and even on high, I saw no ill effects from test strips done at 20x24 magnification when looking at them with a 15x loupe when dry or the neg in the grain focuser:
I did use some 3/4" high density grey foam as mounting block to help reduce vibrations further. I also used aluminum and black gaffer's tape to seal it off. Overall, a variable speed fan makes a lot of sense for this application, I feel it is perfect...
Reporting back. Took the fan out cleaned it with air in the can, lubed the shaft in armature and used heavey duty dens foam and isolated again in its frame. Vibration is consdirbley less. Looking through a grain focuser I see no movement at all. However, I guess one still could feel the fan is running.
Thanks for all the help.
Glad to hear. I turned on my 45MX dichro head this weekend and I can feel the fan running. The fan Beseler uses are not like one ones in computer power supplies. Vibration was a concern for me, but I make pretty good prints on my enlarger so I'm not going to worry about it. The head is 30 years old and it still works great. Had to replace it optoisolator on it though.
No movement in the grain focuser is GOOD :)
My Beseler CB7 came with a Dichro DG color head which has a separate blower that blows air thru a hose to the color head. It doesn't make the enlarger vibrate but it's a pain to locate the blower.
This is a common POTENTIAL problem with Beseler 45S heads. Not all heads experience it, but some do. As you have seen, the test is in the grain focuser and actual prints. Then, if it is a problem, there are solutions.
But YES, you do have to have a fan!
Or, just use the condenser head if you already have one, and someone will give you some money for the 45S! ;)