It says to "lift the

Safety Tip: To prevent any potential mishaps, ensure sure your grinder is fully off and unplugged before using it. Also, if you haven't used it in a while, make sure it's cool to the touch.
Let the Bean Hopper open. Take off the bean hopper from your grinder's top. This is going to reveal the top burr.
Take the Upper Burr Carrier Off: An upper burr carrier is usually used to hold the top burr in place. It is necessary to take out the upper burr carrier. Depending on the kind of your grinder, the precise procedure may change, but generally speaking, it entails undoing a few screws or tabs that secure it. In general, follow these steps:
a. Check the upper burr carrier for any visible screws or tabs. Usually, they're close to the edges.
b. To release the tabs or loosen the screws, use the proper equipment (usually a screwdriver). To prevent breaking the grinder, use gentleness.
c. After the upper burr carrier is released from its locking mechanism, carefully pull or slide it out.
Lift Out the Top Burr: The top burr can now be removed after the upper burr carrier has been taken out. The burr might be secured in place by tiny clips or notches, so proceed with caution and gentleness.
Clean and Maintain: After removing the top burr, you can give the grinder and its parts a thorough cleaning. Make sure you adhere to the cleaning and maintenance guidelines provided by the manufacturer. This often entails cleaning the grinder's parts, brushing off coffee grinds, and correctly reassembling it.
Reassemble: Carefully put the grinder's parts back together in the opposite order after cleaning. Verify that the upper burr carrier is correctly positioned and that all screws and tabs are firmly in place.
Plug in and Test: After the grinder has been put back together, plug it in and make sure it is operating properly.

To clear a stone from the breville/sage grinder first remove the hopper and vacuum any beans out of the top of the grinder, then using a paint brush and the vacuum cleaner clear small debris from inside the grinder cone. Hopefully you will see the stone , you may need to use a torch. Now using a pair of pliers turn the top of the inner grinder cone anti clockwise (that's not the silver nut but the top of the cone itself) hopefully this will free the stone enough to pop it out with a small screwdriver or piece of very stiff wire. If this doesn't work you may need to contact breville/sage as its unlikely you will be able to remove the exterior cone sleeve without damaging it, and if the stone has reached the fine burrs below the coarse feed burr it may have caused serious damage. Otherwise refill with a few beans and check its working ok.

Remove the grinder tray, remove the grinder top and clean out the burrs.
lift the command unit. close and remove the bean hopper. Press in the two thumb tabs either side of the grinder tray and pull the tray forward. If it's not been removed for a while it could be very tight. Push the tray in first then pull.
with the grinder tray removed, take out the white plastic ring that the hopper sits on. Unscrew the two Philips head screws in the top section of the grinder. Remove the screws and rotate the top section anti clockwise whilst lifting off. You should now have access the the grinder burrs. Carefully clean every part of the teeth burrs with a stiff brush or small screwdriver.
turn the tray over and examine the bottom end of the shaft which passes through the grinder. The centre is usually rubber and this can become detached with age. If the rubber is shot you will need to replace the pulley shaft. Check to the tension of the belt From the motor to the pulley shaft
Once everything is clean and clear, reverse the process to reassemble the machine.
you should find it now grinds ok

i have a feeling that probably your tub bearing may be jammed. You can lift the machine at a 45 degree angle take the belt off and try turning the transmission pulley either way, one way will turn free for wash mode and other way will be more difficult but you should be able to turn the pulley so you could see if if your tub turns if not well you just found your problem. You will not be able to repair it b because you will need special tools.
Other probability would be a garment stuck between the two tubs accessable by removing front panel and lifting the top.
lift top by inserting flat blade tool at each end in between top and front push clips and lift top
Front removal twoo screws 5/16 nut driver on each end inner portion of the front panel.
Unclip tub cover and remove and you will be able to see between the two tubs.

Hope this helps.

I am guessing the burrs do not turn. If so, tho rare, a foreign object might have entered burrs and jammed it. Happened to me once. Small stone with beans.

Put the tension back up to about 5. Rethread the machine entirely, and make sure you have the pressure foot in the up position when you rethread. If your getting bunching on the bottom, it's probably your top thread that's bunching up. After you rethread, put a small piece of fabric under the pressure foot, lower the pressure foot, and turn the handwheel in the forward direction and watch the thread as it comes around the bobbin case. If it goes around smoothly, try it with the foot control. If it hangs up as it goes around the bobbin case, you might have a burr on the black plastic bobbin case. Take it out, check for any burrs, sand them down, and try again.

Hi
If you only got the lower burr it won't work. They should be matching burrs.
If you don't do it right, you will damage the grinder. You need a #10 Torex bit.

Insert the bit into the screw in the middle of a very clean grinder. Turn clockwise to loosen. Once the screw is out, pull the burr out, but be careful. There are ball bearings and springs under the burr. Make sure that everything is clean before reassembly. There are 3 holes in the bottom of the grinder. The springs go into the holes first. Then the ball bearings set on top of the springs. Place the new lower burr on top of the springs. A washer and the corkscrew go in next. Insert the screw in and with the bit in place turn (with a little down force) clockwise until the screw drops into place, then turn counterclockwise. It should turn fairly easy. Once you start putting pressure on the springs, try to turn the corkscrew. There is a notch that it slips into in the bottom of the grinder. Once it locks into place keep turning the screw until you start to turn the burr. That should be tight enough. Now reassemble the top burr and adjust.

Hi
Rotate the bean hopper counter clockwise until it stops. Lift the bean hopper out. Remove the outer burr with the wing-lets. Can go back in either way. Clean with air or vacuum out grounds. Use small brush to help clean grounds. Reinstall burr. Line up notches of the bean hopper with shell ( large tab in large slot, and small tab in small slot). Rotate bean hopper clockwise a small amount and test.

This is not a hard procedure, but you have to feel comfortable with DIY projects.
First empty the bean container. Vacuum out any remaining beans. Remove the philips screws from the hopper. Lift the hopper off. Vacuum any loose beans out. Remove the rubber gasket. You may clean this with a mild soap solution. Remove the grind adjustment lever- lift straight up with index fingers under the flange. Turn the outer ring with the holes counterclockwise, lift the center ring with the ears straight up when the outer ring is loose enough. The ring with the ears is the upper burr. Clean with a brush. Don't use water or other solutions. Vacuum the beans chamber and brush clean. Replace the upper burr ring matching the ears with the grooves. Turn the outer ring clockwise until it stops. Pull the inner ring to be sure it is locked. Now turn the outer ring back 13 clicks. Replace the rubber gasket. Replace the grinder adjustment lever- drop the lever flange inside on the outer ring with the lever grip loop over the top at #4. Press the flange with two fingers while supporting the outer ring from below. This seems tricky, but be patient. Replace the hopper and screws. Do any grinder adjustments while grinder is running with beans, it may take a few shots to be back at your preference grind! Good luck!

I know that this machine is sensitive with the lids needing to be securely fastened (both the top and the plastic catch bottom container) maybe that is it.