To change the belt on a post-WWII Kirby vacuum, you have to deal with a sometimes confusing device called a belt lift. You also have to deal with this when removing the nozzle to use the hose, carpet cleaner, or other accessory. To use another head (nozzle) or hose on the Kirby motor unit, or change the belt, you must remove the head from the rest of the vacuum. WARNING! Always unplug any electrical appliance before working.
To remove the nozzle, first lift the headlight. Next, turn the belt lifter (the thing in the front that can turn about 3/4 of a turn) counterclockwise as much as possible. This should lift the belt off the motor shaft. In many Kirbys some arrows say belt off will line up. Some brown models in the early 70’s had a window on the belt lift that said belt off. Now you can open the latch on the main body that holds the mouthpiece. This is right in the center above the top of the mouthpiece. Now you can remove the mouthpiece. If you look inside the hole in the back, you should see that the steel hook on the inside is at the top and the belt is hooked to it. This is how it should look when you are ready to put the mouthpiece back on. If you are attaching the hose or other head, I recommend that you turn the belt lift back to the belt on position, so you do not stretch the belt.
If you want to use the hose, hook the bottom of the end of the hose behind the small shaft under the motor shaft on the main unit, tilt it up and secure it at the top. If the small shaft is not centered (the same amount of shaft sticks out on each side), tap it gently until it is centered.
Belts stretch and slide, especially on thick rugs. The genuine Kirby belt for machines built since 1981 has a tread on the inside to help reduce slippage. Also machines made since the mid-80s have had a green LED on top of the edge of the nozzle that lights up when the brush is spinning at a good speed. If you have an older machine (or its green light mechanism is broken), we recommend that you routinely change the belts every 3-6 months as they will stretch. If your light is on when you are using the machine with the correct height adjustment, then your belt is suitable.
With the nozzle out of the machine, as described above, to change the belt, turn the belt lifter to belt on if not all is ready. Then remove the bottom plate. On pre-G series machines (G series are Generation 3, 4, 5, 6, ultimate G, Ultimate G Diamond, and Sentria) (which came out in late 1989), the brush will be attached to the bottom plate. Gently pry off one end, remove the strap, slide a new strap over the brush, and reinsert the brush into the bottom plate. The screw heads must face down for you to tighten them. On Kirby G-series, the brush is on the nozzle instead of the bottom plate. There is a number 1, 2 or 3 facing outwards, there are also 1, 2 or 3 notches at the end of the square. The same number should be facing out on both sides when reinstalling. Cut off any hair. Replace the bottom plate (some had latches, others just push in). Push the brush up. Put a ruler at the bottom. The bristles, when pointed downward, should hang past the straight edge about the thickness of a coin. We have machine 1 of the G series that lays less bristles. As the brush wears out and not enough bristles hang down, position the 2 towards the bottom, if still not enough, all 3. On older models, tighten the screws until a bristle coin thickness hangs below bottom plate.
IF you took out the entire brush to clean it more thoroughly, which end goes where it matters. The bristles are angled so that as the brush rotates from front to back, the dirt is directed towards the center. One end is larger than the other, so it should be impossible to position it incorrectly. BUT, if someone removed the ends to clean the bearings and reversed them when they put them in, then the brush will not work well. Also, on pre-G series brushes, the large end can be forced into the small groove, although the end is broken. Also, in later machines in the mid-80s, there is a magnet at one end of the brush that induces a current in a coil of wire that lights a small green LED on the nozzle. If the magnet is not at the end where the coil and the LED are, something is wrong. The ends can be removed and changed to look good. IF you decide to remove the ends to clean the bearings, remove them one at a time and replace them before removing the other end.
Then when you’re ready to put it back on, turn the belt lift to the belt off position, making sure you have grabbed the belt (you can see through the hole in the back). Then hook the nozzle over the shaft (making sure the shaft is centered, see paragraph 3) under the motor pulley on the main unit, tilt it back and fix it as you unhooked it. Then turn the belt lifter to the belt on position. This should drop the belt onto the motor shaft and it should be ready to go.
The carpet cleaner and handy old butler accessories also have a belt lift and hook and unhook in the same way from the front of the machine. Leaving the belt in the air on the hook will stretch it.
