Hi, I am totally stumped by my Maytag dryer problem. The unit dates from the late 80's and my wife loves it and the washer bought with it. Recently, it stopped heating at all and I could see through the inspection panel that the gas valve was not opening to let gas in to the burner. I then replaced the coils operating the gas valve and the burner resumed working.

However, after doing this, I found that, although the dryer would heat and dry well, the timer would not advance in the sensor mode and the dryer had to be stopped manually. I have tried the timer in the timed mode and, although the timer advances in that mode, it does not heat and dry clothes. As I rotate the timer knob, I can feel when the timer motor is on and when it is not, such as in the sensor mode. This dryer predates having sensor plates in the dryer drum. It appears to have only two cycling thermostats, a thermostat "switch" and a fuse. I have checked for clogging in the dryer exhaust and the external ducting and find that it is blowing quite well.

At this point, in addition to the gas valve coils, I have replaced the timer and the two thermostats, with no fix. Other than this problem, the dryer still works extremely well and I would like to keep it going as long as possible. Can you help with this?

So, how much have you spent to repair a 30 year old dryer? New basic Whirlpool dryers are $400.

Are these the coils you replaced?

Whirlpool 279834 - 'M' Series New Style Coil Kit | PartSelect (http://www.partselect.com/Models/DG512/Parts/PS334310-Whirlpool-279834-M-Series-New-Style-Coil-Kit.htm?SourceCode=22&SearchTerm=&ModelNum=DG512&sSearchTerm=Timer-will-not-advance)

http://www.partselect.com/334310-1-M-Whirlpool-279834-M-Series-New-Style-Coil-Kit.jpg

The sensors get blocked from sensing when the dryer is dirty and that is your problem now, in fact, the sensors could even be bad. If your dryer has thermistors then you will have to test them with a thermometer and a good digital multimeter. It's pretty easy to do as you just measure the resistance of the sensor while testing the temperature, too. You can do it with hot water. Most of the time just cleaning it well with soap and water cures the problems and makes it run like new. You also have a hi-limit safety. The safety is behind the drum, but NEVER install a safety without first thoroughly cleaning every part of the dryer. You need to totally tear it down and scrape out and wash all of the parts except the motor, which you vacuum out. You have to totally tear it down piece by piece. Halfway cleaning it will not work because all it takes is one clogged up air passage or dirty sensor. You can go to YouTube to see videos on how to take it apart, but do a very good job or it will fail again quickly. I would get a new belt and change it while you have it apart and get some white lithium grease and grease any bearings you find. The support rollers are greased by pulling the pin and greasing it and greasing the inside of the roller. You need to clean out a drier every two years, at least, according to the manual. You just unplug the wires from the sensors and remove ductwork that they are attached on and clean the entire thing with soap and water. Make sure you go all through the dryer and get all parts like the blower fan and housing (it has to be scrubbed and washed out), vacuum out motor well and clean exhaust. Mark all wires you unplug so you know where they go. If you leave any dirt in the ducts it will blow another fuse quickly or will not maintain the temperature correctly. This is an easier job than you would think. Make sure to clean around all of the sensors, if it has them. Also, change the belt while you have it torn down so you won't be doing it later. See: http://www.youtube.com/watch?v=A6wmD502-xE and: http://www.youtube.com/watch?v=OBNDbyRm68M&feature=fvsr
http://www.youtube.com/watch?v=a73HTFkcB90&feature=relmfu
Changing parts that have nothing to do with the problem will not magically cure any problem. Here are some manuals: https://dl.dropboxusercontent.com/u/8010163/Maytag%20Dryers.zip
https://dl.dropboxusercontent.com/u/8010163/Electrical%20Theory%20and%20Diagnosis%20of%20Major %20Appliances%20Service%20Manual.pdf
https://dl.dropboxusercontent.com/u/8010163/How%20to%20use%20Test%20Equipment%20Service%20Manu al.pdf
If you will learn proper troubleshooting techniques you will save a lot of time and money. About 95% of problems with dryers are from dirt buildup, wear on the belt, and the grease drying up. All dryers have some type of temperature sensors and are very sensitive to dirt buildup. If you will clean it once a year and change the belt and grease it you will have almost no problems.