Electrolux Upright
The above UR looks good and is a later model with many improvements over the early ones.I have seen many and can add some general info----
1.Full (or clogged ) bag is light at base without shut off.
2.Not sure? but similar to tank and good for most rooms.
3.Motor cannot be seen without special tools,knowledge and skill to properly take off upper body then motor cover.The good news is that motor or bearing problems are very rare unless abused or heavy use.The brush is easily seen and bearings at end can be cleaned with just a phillips screwdriver.The 2 belts are on a magnetic clutch and almost never need attention.(Unlike a current 2 belt model that is known for pretty colors!)