I just used my DeWalt DW433 3"x21" vs belt sander for the first time. The belt sander turns fine till I lay it on the item that needs to be sanded. It continues to run but the belt rollers stop spinning and the belt quits spinning. It stops spinning even with no pressure applied to the sander. I have tried all the adjustments but nothing I have done works. I am unable to finde my owners manual and I can't even find one online.

The drive drum or idler drum???

If the sander is otherwise in good shape, and hasn't been abused, I'd replace the brushes.

It sounds to me that you have used the sander a lot and the vibration has broken a wire or it's about to break on the field windings. The brushes you need to look at to see if worn. But I kind of think wire problem. I had this happen on mine and opened it up to find this is what happened. The sander would be turned on and would not operate until I turn upside down and it would work. This is great if you are sanding upside down but this is just a sign that you are on borrowed time as this will eventually not turn on at all. I was able to fix mine with new wire crimp connection and solder with heat shrink material. If not you can order new field winding if this is what is wrong. Cleaning up the sander won't hurt either. You might want to see what a new sander will cost vs. part. Good Luck!

If you release the belt that would give you more room to get the cord out. When you releas the belt it brings the rollers together which loosens the belt.

You might try Dewalt. I have a Black & Decker weed eater that had a broken belt and I had to order it from Dewalt. I was told that they had some kind of merger. Ordered it and it worked just fine.

Unfortunatly that sleeve is not available, you will need to purchase a whole new drive wheel. The Drive wheel is $9.66 from DeWalt Service Net. Porter Cable, Delta & DeWalt are all owned by Stanley Black & Decker, you can contact DeWalt Factory Service for all parts. 1-800-4-DeWalt You can order the parts on-line, over the phone or though a local service center. The website is www.dewaltservicenet.com Below is the parts diagram for your sander. The part number for the drive wheel is A16439
http://www.dewaltservicenet.com/Products/DocumentView.aspx?productid=65594&typeId=15450&documentId=34604

To change the belt, you must release tension of the rollers by pushing the front roller straight back until you hear it click and lock in position to change paper. Remove old paper and replace with new paper. Make sure if new paper has directional arrows to install properly.
Now you must release the front roller to put tension on paper. To do this push the front roller from the side that has the adjustment screw. This will release the front roller and allow it to go back into position. Be careful as it pops back quickly and with some force.
Turn on sander and adjust centering of paper with adjustment screw found near the front and side of sander.

is there a plastic cap on the end of the screw?? you can go to Makitatools.com and with your model number download a breakdown for the tool. Let me know and I will try and help further.

Seems time for a new sander.

Instead of removing the drum, remove the belt and the cover over the gearbox. The gearbox cover is normaly fixed in place by screws around the drive pulley. There may be a couple of screws under the pulley, if so they can be accessed via holes in the pulley wheel itself. Check for worn or stripped gears. These gears can be replaced if need be, but if this is the case make sure you remove and clean out all the grease first and replace that aswell as it may contain bits of teeth that have come off the faulty gear. As far as I know belt sander drive rollers can not be removed without removing the drive inside the gearbox first.