I have a Maytag DE512. It takes an hour or more to dry.
Venting is not a problem.
The dryer appears to heat to ~150 degrees. I think the problem is that "cool" portion of the cycle is too long. In other words, some times when the dryer is running it will be cool, but at other times is is plenty warm. As stated above the heat seems adequate.
This leads me to believe that the problem is with the cycling thermostat. Does this sound like a proper conclusion?
If so, there appear to be three thermostats on this dryer. One on the heating unit and two on the exhaust side. The exhaust side thermostats are 150-25 and 140-20. I could not see the label on the thermostat on the heating unit. The question then becomes which thermostat do I replace?
150 is hi heat setting, 140 is low setting for more delecte clothes, the one on heater is the safety thermostat stop a runaway element, on your old dryer, you should change all 3, cheap insurance!!!!!!!!
Which Thermostat? 
