The heat is normal, the two 3K, 10W resistors each dissipate about 3.5 watts, so there is a 7 watt heat source just below the chassis plate. The vent holes do help, but as stated earlier, they won't work unless the rubber feet are used to raise the wood base, which will then allow for convective airflow.. The two 270 ohm resistors in the PSU also dissipate a 1.73 Watts each. So there is a total of almost 9 5 watts of resistance "heaters" under the chassis plate.
I found that the tranny and the tubes run at relatively mild temperatures, the 6080 is loafing along at about 5W total plate dissipation, plus about 16W of filament consumption.
HTH
/ed B in NC