Backstory:

Recently my wife noted that the towels were not drying very well in the dryer despite the fact that the drum was warm and we could see the orange glow of the heating element.

I pulled the dryer out and checked the hose - there was no obstruction in it. It has one of the lint filters that is removed from the top of the unit - it usually has a light covering of lint from top to bottom in the filter and she checks this every time.

So I unplugged the dryer, removed the back panel and then unscrewed the metal lint chute assembly piece that runs from the blower motor to the location of the lint filter.

It was filled with lint and little tissue balls and a few small things that got through the holes in the drum and found their way into that mess. Anyhow, cleared that all out, vacuumed it all out and reinstalled everything. Figured that might be the problem.

Didn't seem to fix things - the dryer works but just takes forever.

Today, I used a meter and check the continuity on the dryer thermal cutoff and the dryer high-limit thermostat. Both Read 0 ohms with the continuity check.

I also checked the heating element's resistance - my meter read 10 ohms.

I reinstalled the lint chute assembly and threw a damp towel in the dryer and ran the dryer for a few minutes at different settings and watched the heating element with a small mirror. I noticed that the element was turning orange near the top of the element and at the very beginning of the coil (see the picture to see where I mean) but the bottom coils (maybe the next one up - it was hard to tell) were not orange. (see second picture to see where I mean).
[IMG]http://flic.kr/p/9SNuC7[/IMG]
[IMG]http://flic.kr/p/9SKCSF[/IMG]

The blower's blowing plenty of warm air out, the drum turns fine, I see the element cycle on and off periodically.

I haven't checked anything else with a meter yet, mainly because I wasn't sure what else to look at.

Ideas?

Thanks,
Matt

Since only part of the element is heating, I would check to see if it is grounded.

Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can doo all sorts of things depending where and how it is grounded.

Your links did not show up for some reason.

Here are your parts
Replacement parts for WHIRLPOOL LEB6400LW0 RESIDENTIAL DRYER | AppliancePartsPros.com

See the attachment for the wiring diagram

Unplug the unit and disconnect it from the vent system.
Now try a run.
If it now dries OK odds are the vent system needs checking/cleaning.
Be sure to check that the louvers on the outside of the house open correctly.

If you do not want any lint in the house.
Take a pair of pantyhose.
Put one leg into the other and then attach this to the dryer's vent.
Leave enough room so the pantyhose can balloon out like a windsock.

Both the above will let you check the temperature and the air flow.

Your main thermostat (Item 8 in Section 3) should open at 155 degrees F and re-close at 130 degrees on high heat so your exhaust temperature should be in this range on high heat.
If you have a thermometer check it.

You will see that the main thermostat is 4 wire. Two of these are the heater contacts the other 2 is a built-in heater (4,800 ohms). The heater adds heat to the thermostat which causes it to cycle more often reducing the units main heater output.
Perhaps it is always on for some reason.
Unplug the unit and one wire to the thermostat's heater. tape the wire up so that it cannot short to anything and then give it a try.

Check your lint filter sometimes it can get coated with fabric softener residue and has to be cleaned with soap and water.