Hello - I have a Miele T250C Tumble Dryer, which is taking much much longer than usual to dry. It is 8 years old and has been heavily used, but still under warranty as we got a free 10 year warranty. The filter and airways are clean, and the dryer isn't stopping all the time (which it does when the airways are blocked) - it just takes a long long time to dry. It also makes a very repetitive churning noise (ba-ba-dum, ba-ba-dum etc).

1...You may have more than one problem on your problem with your dryer not heating.
2...Your noise (ba-ba-dum) is being made by your drum rollers that probably have flat spots on them and is in need of being changed.
I will include two solutions to your two problems, I am not sure if the disassembly of the dryer that I am going to send if for will be applicable to your dryer disassembly but it may help
-----------------------------------------------------------------------------------------------------------------------------------------------Problem 1...Not heating

ALWAYS UNPLUG YOUR DRYER BEFORE ATTEMPTING TO DO ANY WORK ON IT.
Check to make sure you are getting full 220 Volt power to the dryer, if you are then:
Check your Wiring
Often the main wiring connection from the house, at the dryer, burns and the connection breaks. If this has happened to your dryer, you need to replace the power cord and the terminal block inside the dryer to which the wire is attached.
Check the Door Switch
If the door switch or the door-switch actuator is defective, the dryer won't work and you need to replace the failed component. The switch is inside the dryer main housing near the door frame. Sometimes you need to raise or open the top or front of the dryer to reach the switch. Check for continuity you should have none with door open, and should have a reading when closed. If not replace the door switch.
Check to make sure you heating problem is not a lint build up in the discharge hose or the dryer,as this condition can cause heater/thermistor problems such as overheating of the heating coil leading to failure of the coil and burnout of the thermostat/thermistor due to overheat.
Remove the back/or front just under the door of the machine and try to locate the air duct going from the blower to the drum. Normally inside/outside the air duct you will find the heating coil and the thermostats/thermistors. Once you have located the heating coil, remove the two wires from it and check the coil with an ohm meter across the two terminals of the coil.
You should read continuity across the terminals, if not you will need to replace the coil as it is faulty.
If the heating coil is ok, then:
You can check the thermostat/thermistor one at a time by removing the two wires and taping them together with electrical tape or with an ohm meter to test the thermostat/thermistor. (Should have/show continuity)
If the coil heats up then replace the thermostat/thermistor.
(Thermal fuse.If it overheats the dryer will not operate. It's located on the blower housing. It cannot be reset. A vent clogged with lint can cause it to overheat. You can test it with an Ohm meter or continuity checker, if no continuity, replace it)
DO NOT LEAVE THE WIRES TAPED TOGETHER AFTER THE TEST.
This could cause a FIRE, as you have removed the safety of overheat from the machine.
Right after replacing a dryer element, always run the dryer on 'air fluff' / 'no heat', and go outside to verify there's plenty of air coming out your vent system.
If the vent's clogged, that new element can burn out very quickly.
For video and pictures on how to replace the element go to the following website:
davesrepair.com/DIYhelp/DIYreplacingWPLdryels.htm
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Problem 2...
ALWAYS UNPLUG YOUR DRYER BEFORE STARTING ANY REPAIRS
Your problem sounds like drum rollers have flat spots on them or in need of lubrication, or maybe your drum belt has slipped off of the idler arm pulley.
If you have a front loading machine,

Remove the electrical console that holds the timer switch, start switch, etc. from the top of the dryer.
Be REAL CAREFUL not to knock any of the wires off of the timer switch.
Then remove the top of the dryer.
Remove the front of the dryer. This will expose the drum and belt.
Remove the drum and belt and this will expose the drum rollers, idler arm
pulley and motor.
Now is a good time to check the belt to see if it has slipped off of the
idler arm pulley and also to check the belt condition for wear.
Be sure to note the route of the belt, this will come in handy when you go
to reinstall the belt.
Check your drum rollers for flat spots or wear, if they have flat spots
or wear on them replace them.
If the drum rollers don't have flat spots or wear on them then they probably
only need lubrication. Lubricate the shaft of the rollers with a good grade
of machine oil such as 3 in One oil.
Reassemble the dryer, plug back in. This should solve your noise problem.
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