.................... my 1602n still air , even though it was giving me great hatches on my first two attempts at hatching . While it ran fine and cycled at 99 to 100 where the eggs set in the turner , I had discovered the edges and corners were running too cool . Keeping the eggs in egg cartons during lockdown solved the problem of hatchlings rolling the eggs to a corner , but I thought a fan might alleviate thermal stacking and make the edges run warmer too .................. possibly even stop me from having to adjust the wafer as the developing eggs started giving off heat of their own and causing heat spikes . After adding the 12 v fan wired to a 3 v transformer for a gentle air movement , I noted edges and corners were very close to rest of the bator at floor level , staying at steady temps there , and shut it off . I decided to give it a test run before my next hatch . The fan's mounting screws had fit perfectly through the four smaller vent holes , and with the slightly larger one left in the center with the fan blowing up at it , I figured it was still getting about the same air exchange . At the center of the bator , at what will be mid egg level , I discovered the best temps now cycle from 97.8 to 101.1 ; compared to a steady 97.3 at the floor , and drilling two more vent holes did not help . I guess the fan needs to come out and the two extra holes filled back in ; so much for fixing something that ain't broke .