I exchanged my Ender 3 Belts for GT2 Belts and then i got in the Situation, how to hold the Belts in place, without help.
So i made a kind of self fixing Beltfix
Its Printable on the FDM also on a Resin Printer.
You fidget it throug one Hole and put it back into the teath, and pull it slowy back so the teath grab into each other and then, it will hold by itself.
The author hasn't provided the model origin yet.