If it is a typical front loader there is a little panel on the front below the door.
Take a flat screwdriver and slip it in below the two little metal pieces towards the two ends.
The little access panel should then fold forward and you should be able to see the motor, idler pulley and belt.
The screeching sounds like the idler pulley is bad, they are not too hard to replace, the banging noise may be one of the drum wheels, the drum rides on little plastic wheels and if one breaks the drum jumps every time it hits the bad spot.
Check the felt seals too, I finally replaced my dryer because it was leaking so much heat out of it that I had to run the exhaust fan whenever I dried a load.
Try to push the interlock button and run the dryer so you can see what is happening.