Gleaner
The gleaner switch moves the bar on the rug side of the tool from smooth (off) to the grooved side (on) it works well on most types of carpet to better pick up lint, pet hair, and also just lift the pile. While this tool is still made today, the gleaner is gone and it is a smooth bar, but in the 70s it was changed to a non switch style with finer diagonal grooves. I’m not sure why they went to the completely smooth style as the finer diagonal grooves style worked on all types of carpet but wasn’t quite as effective as the original but better than nothing. The original style like yours worked on most carpet but loop type and some others it would just grab and get stuck so then you would have to switch it off. It should never be on if that side is used on any hard surface for fear of scratching it and damage to it should it be dragged on cement which shouldn’t be done anyway. It really is something that became obsolete once the power nozzle was introduced which does a far better job of removing clung on lint, dust, hair and threads and also fluffs up the nap.
The hose handle holes are for suction control. There may be too much suction when cleaning things like small area rugs or drapes and so opening it a desired amount would allow the tool to glide and not stick as much to the fabric or surface while still cleaning to a decent degree. Some expensive modern canisters now have a motor speed control for this purpose but for single speed machines this is how suction can be reduced if desired or needed.
Nice to see you have a modern rubber hose, the old braided ones often leak making the machine not very effective. Looks like the original hose handle and machine end were reused with adapters to fit the rubber hose. I’ve done the same with a plastic hose.
If you don’t know how the automatic control works and proper ways to set it...I can give you tips. Normally it should stay on the 3 or 4 setting. It controls when the bag door should pop open indicating time to change the bag. It should never be left set on 6 permanently as running the machine with an overfilled bag will be allowed and put strain on the motor shortening motor life due to overheating.
Jon