How to change the Master Disposal Rubber Bands / Belts on RISO RP

This a common problem on RISO RP3100, the rubber band that allows the master to be removed breaks because of the deterioration of the rubber. 
I found an old explanation from PrntNow

If you want to find the real belt for replacing it, you can buy it on aliexpress but it will cost 10-20 € for 8 and take a month to deliver.
Instead, I just bought a pack of classic rubber band, and decided to use the 30 and 75mm to replace the small and larger belt.

It works perfectly fine !

The actual sizes of the Rubber Bands you can find in the parts list, for the RP3700 its as follows, so you might want to choose different sizes:
larger belt: Part Nr. 628-21521-004, 2X152mm (ca. ø 50mm, length 76mm)
smaller belt: Part Nr. 628-20900-001, 2x90mm (ca. ø 29mm, length 45mm)