Used dryers almost always come clogged with lint and debris.

This is a pretty good machine and I think you can make it work for you but you are going to have to spend a little time with it and take it apart. Fortunately this is not difficult.

1. Take off the back by unscrewing the screws that hold it on.
2. Open the lint filter lid, take out the filter and take out the two screws you find in there. These hold the top to the cabinet.
3. Insert a putty knife or screwdriver in the gap at the front between the top and the front panel and flip up the top.
4. From the back take out the line chute if you can. One of your problems is the lint chute is filled with lint and debris.
5. Take off the front, release the belt and take out the drum. You should be able to find out what is causing your brown stains.
6. Clean the lint out of the heater box and the intake vent.
7. Use a good degreaser to clean the lint filter.

This should fix your problems, but if you want to do some preventive maintenance, and I think you should, replace the idler, belt and rollers.

Put it back together and you should have a dryer that you can move to your house when you buy it and use it for many years to come.

Good luck.