So, having recently gained access to a laser cutter, I built a tailgate that holds six fans. A center fan and three spaced evenly around it. Two small fans are in the upper corners blowing on a bit of hard paper velcroed to the box to divert air across the mirror. It's recent but seems to work well. I couldn't see any vibration at 380x. I haven't had good enough seeing to go higher than that but I rarely will.
I bought a 2004 15” Classic back in June, and just recently discovered how important cooling the mirror is after I started seeing double images, presumably due to a boundary layer on the primary. The OEM fan (?) is marginal, and as I discovered it introduces significant vibration into the chassis and image. So maybe I can do something like this as my first upgrade. Paul, did you use any particular brand / type of fan to keep vibration to a minimum? Thanks so much for posting the great photo - you really did a great job with the laser cutter and cleaned up the back of the scope magnificently!
