not drying

Everything seems to be working properly but the clothes are not drying - it takes several cycles to get a load done. What should we look at first, second, etc. to fix.

Here are your parts
http://www.appliancepartspros.com/partsearch/modelsearch.aspx?model=DVL223EB1WW

Often this is just a dirty/malfuntioning vent system.
Check and clean it.
If it is a royal pain to do you may want to run the♦ following test first.

Undo the dryer from the exhaust
Run a load
If the load dries correctly then you have a vent problem.
Clean/check the vent system. Make sure the outside louvers open fully.

If you do not want lint in the house.
Take a pair of pantyhose, put one leg into the other and attach this to the dryer exhaust.
Leave enough room behind the dryer so it can blow out like a windsock.
Run a load.

Both the above will allow you to check the air flow and temp.
Also the above is NOT recommended for a gas dryer due to possible carbon monoxide problems.