Dan,
This is a great question. My experience is that the critical parts for cooling consideration are the input amplifier U3 and U4 (Schmitt amplifier). These are highly susceptible to shortened life due to heating. Of the 200+ units I have refurbished, interestingly, those that had underpowered fan replacements also had one or both Schmitt amplifier chips not working. So my suggestion is to replace the fan with one of the proper air flow. Especially considering that the Schmitt amplifiers are no longer available.
Regards,
Joe, KN5U
