The M3 Motor Belt connects to the M3 Motor, which drives the conveyor of the PhyzBatch. This guide will show you how to troubleshoot a loose M3 Motor Belt or, if required, replace it with a new belt.
If your machine starts making a knocking noise, it could be caused by the M3 Motor Belt skipping. This could be due to the belt not having enough tension, causing the motor belt to be loose, or due to missing teeth on the belt. If your machine is making an unusual noise, you should first determine where the noise is coming from. It could be from a faulty bearing or a broken cog on the conveyor. If those have been ruled out, and you have determined the knocking sound is coming from the M3 Motor housing, then it's likely that the M3 Motor Belt is skipping.
You should first determine if the belt needs more tension or if it needs to be replaced. When replacing the belt, we suggest first disconnecting the scanner unit from the PhyzBatch, as it makes it easier to work on.
Inspecting The Belt
To inspect the belt, first remove the side panel on the motor housing. To do so, use your 2mm Allen Key to remove the three bolts pictured below.
Once you have removed the panel, pull back the foam to reveal the belt drive system. Once the foam has been moved, you can also inspect the motor belt.
If your machine has this upwards screw installed (not all of them do) please remove it before proceeding. It does not need to be reinstalled afterwards.
Next, inspect the belt. If the belt is damaged and teeth are missing from the belt, you will need to replace it. If the belt is undamaged, it may just be loose, and you can add more tension to the belt.
Add tension to the belt
On the side housing panel, there is a rubber plug called the bushing; it puts upward pressure on the motor to help keep tension on the belt.
Screw the plate back on while pressing upwards on the base. There's a bit of play with the plate, and the goal is to have it as high as possible for maximum tension. If the plate is high up on the two points pictured below, that's the correct location.
If the knocking sound continues, take the plate off again and wrap one or two layers of duct tape around the rubber bushing to increase its diameter, then screw the plate back on following the steps above about positioning. If this does not resolve the problem, you will need to replace the belt.
Replacing the M3 Motor Belt
To replace the M3 Motor Belt, you will first need to remove the conveyor cover from the PhyzBatch. Next, you will need to disconnect and remove the Scan Blaster module from the chassis.
Next, please remove the side conveyor motor housing panel from the conveyor and then pull back the foam to access the M3 Motor Belt. Once you have the housing removed, you will next need to remove the four screws from the belt spool casing using your 1.5mm Hex Key.
Once the screws have been removed from the spool casing, you can remove the casing. Be careful when you do so, as the bearings may fall once opened. Next, remove the bearing and place it aside with the screws.
Next, remove the connector plate from the conveyor chassis.
Use your 2mm Allan Key to remove the plate, making sure not to lose the screws or the spacer when you remove it.
Once the bearing plate has been removed, you then want to remove the tension on the lower spool/pulley by loosening the two grub screws set into the gear wheel.
Once the spool is loose, push the central shaft out through the spool. If needed, you can grip the corresponding gear on the opposite side for leverage.
Be careful not to lose the sleeve, which may come out once the spool and shaft are separated.
Next, lift up the sprocket spool cover and place the new belt around the sprocket spool, ensuring that the teeth of the belt are facing inwards.
Then return the bearing to the original position on the shaft, and return the spool cover to its original position as well and secure it in place by reinserting the screws.
Next, ensure the sleeve is placed on the shaft. If it's secure, you can then push it through using the orange gear on the other side of the conveyor. Then return the gear spool to its original position and ensure that the new belt and the connecting drive belt are in the correct position. Then use your Hex Key to push the shaft out from inside the spool. 
Once the above steps are complete, check the following.
- The sprocket shaft is fully pushed in.
- The spacer sleeve is replaced.
- The inner belt is on the sprocket spool.
- The outer belt is on the sprocket spool.
Next, reattach the connector plate we removed earlier.
Then ensure that the O-rings on the shafts are returned to proper alignment so that they're both in the correct position on the dowel and are aligned and parallel with each other. 
Next, tighten both of the grub screws inside the spool to create tension on the shaft.
Now that you have replaced the belt, you can put the plate assembly back on. Please put the plate back on following the positioning steps from earlier. Once the plate is back on the conveyor, you can reattach the scanner unit to the conveyor. The belt replacement is now complete.