The dryer suddenly started running cold - it would turn, the timer worked...but no heat. My wife mentioned that it had been taking longer and longer to dry a load of clothes....

Popped the lower cover off the dryer, found the thermal fuse and thermostat mounted on the heating tube. Removed the screws with a nutdriver, swapped wires to the new parts, and reinstalled. Then I spent 30 minutes vacuuming 13 years worth of lint and crud out of the machine - it was pretty gummed up in spots, which is probably the cause of the failure.
I have a 25 foot run of hose from the dryer outside, so I replaced that with 4" metal ducting. Clothes dry much faster now!!! Maybe my electric bill will go down (fat chance :) )