Putting a fan in front would not be a good thing, I think.
The problem with this is that you would effectively be blowing the always present dust and other particles into the unit. Sure they'll get there anyway but pushing them in is never helpfull. Also, the heat inside the machine would hardly change since you rely on radiotion heat transfer from the inside, stale air to the metal housing which you would be cooling slightly better with a fan on top, but normal steel is not as good a heat conductor as aluminium for example.
If your unit does have vents on the bottom I think your best bet would be to take a high presure PC fan (like a noctua) en place a filter either before or after the fan, as long as it is before the VCR and effectively push air into the unit. The airflow would be minimal but the added benefit of doing this is that you effectively create over presure inside the VCR which means that dust cannot get in
This is how they do it on industrial computers and machines in dirty environments. I have been thinking about doing the same with my JVC but for it to be really effective the fan would have to run 24/7 since it would otherwise defeat the purpose.
I have wondered myself about the winding/rewinding. At this moment I use an old POS VCR but I am worried that the lesser qualitiy of that unit actually affects the quality of my tapes!
I do know that my first JVC S-VHS purchased over
ebay had a worn loading mechanism so they can wear out!
