Here is the rebuild of the disc spring in the gearbox off my 912UL Rotax motor.
First is the removal of the fuel pump.
Using a rubber mallet you loosen the gear box from the locating dowel pins
This is the engine side of the box.
This is the driven side of the box.
Here are the internal components of the driven side of the box. Fifth from the right are the two cupped shaped washers that make up the "disc spring", which holds pressure on the assembly.
The old washers are .2015 and .203" thick. The new ones are .2145 and .2215 thick. Quite a difference. I'll take some more photos of the reassembly and hopefully successful results tomorrow.