I have a 3-cycle timer on my Amana Dryer. The timed dry heats up, but takes more than 90 minutes to dry (I have to do 2 cycles of 45 mins each since the max is 70 mins). The More/Less Dry timer cycle does not advance, but clothes do get dried if I leave it at the More Dry setting and remember to take it out when done.
If you are certain you are getting the appropriate amount of heat, that the drum is turning and that the exhaust fan is blowing,
Then you should open up the dryer cabinet and exhaust cover and clean out absolutely everything, paying particular attention to the air exhaust system. A vac and an air compressor spray are best, but work with what you have. (If you have not done this you are going to be amazed at what is in there!)
After you do this, try a load, and post back the results.
Good luck.