I've got five or six Watson loaders, and I reload casettes thrown out by the one-hour in our area. Some of them even came from disposable cameras. 🙄
No issues EVER reloading in the light with the carts and the Watsons. I use Scotch Magic semi transparent tape. Just make sure you tape it on squarely (I match up the perforations). If you get it going crooked, tear it back apart and start over. And go slowly until you get things worked out.
After it's secured, roll -gently- until the taped area is sucked inside the cartridge. Then close up the Watson and wind-on slowly.
It's a no-brainer 😛 Never ruined a roll and I've done hundreds this way