After the Winter Update 2023, it is possible to obtain the first piece of the disc to assemble a new replacement key. Go to Sandomo and say the keyword Lost and he will give you a new Piece of an Ancient Disc and a Crumbled Dary Page. When you use the diary page, the locations of the other pieces of the disc will be added to your map.
The second piece of the disc is at Folda. Go to the island and go down the stairs at the place marked on the map below:
Now walk to east and go to the place marked with the red exclamation mark:
Now use a pick or equivalent between the tiles covered with debris and go down the hole:
Open the Pile of Bones to get a Fragment of an Ancient Disc:
The third and final piece of the disc is at Oramond. You will need 5 nails to get it. Go to the Minotaur camp:
Follow the path shown in the image below:
Now do the following steps:
1- Use the crate to get wet boards:
2- Having the 5 nails in your inventory, use the wet boards to create a raft.
3- Now use the Sturdy Bollard to travel to a small island:
4- Use the pile of bones to get the final piece of the disc:
With the 3 pieces in hand, simply combine 2 of them to create The Key Intihuatac:
Source: https://tibia.fandom.com/wiki/Adventures_of_Galthen_Quest/Spoiler#The_Key_Intihuatac