Step 1: Using 2.5mm screwdrivers, remove rear shock mount by taking away the two screws. Then, remove shocks from rear arms.
Step 2: To access the belt, the top part of the transmission case need to be removed. To do so, with help of the 2mm screwdriver, remove four screws, two at the back and two in front - connecting transmission case-top desk. From here you can directly access the transmission by flipping backward the camber plate and removing the upper case made of two aluminium bulkhead and a plastic part. As well, remove the differential.
Step 3: To finally access the belt, remove the two screws in the front section of the top desk with the 2mm screwdriver. Also in the same area, using the same screwdriver, remove to carbon plate retaining the two ball bearings and the axle
Step 4: Remove the mid transmission cover with the 2mm screwdriver, mid transmission allowing the same rotation of the motor and rear wheels.
Step 5: With the 5mm nutdriver, remove the upper pinion of the mid transmission. At this stage, belt can be set free and replaced with a new one (Ref U4494 if you run with motor in forward position, Ref 4223 if you run with motor in backward position).
You can evaluate the belt wear with its color. Julien replaced the belt after three race meetings and the belt still have decent teeth shape.
From there you can operate backward for Step 5 to Step 1 but make sure to set free the belt tensioner when you reposition the differential hence you'll avoid tweaking the chassis. Also, reinstall all the differential area before resetting the top desk.
Last but not least, adjust the belt tension.