Loud Squeaking Noise

My dryer makes a loud squeaking noise during part of drying cycle, it stops for a while, then repeats. Any ideas on what may be causing this problem.
Thanks
BM

Here is the parts breakdown
http://www.appliancepartspros.com/partsearch/modelsearch.aspx?model=MDE5000AYW

And here is a service manual
http://www.servicematters.com/maytag_library/docs/16023110.pdf

Could be a number of things. Check the front glides, rear suspension rollers, idler wheel, motor, blower wheel.
Also check for anything stuck between the drum seals and the case.
Check for slop in the bearings and wear on the shafts, the most likely culprit is the idler wheel. Also check the belt.
Give the interior a good cleaning.
Might as well clean and check your vent system while you are at it