1. Turn dial to 25# and then lift kettle off base
2. Remove the 10# weight that is sitting on base and put to aside.
3. Put the kettle base back on the base and turn to 40# (with the intervening 10# weight)
4. The kettle is now 30#
The replace the weight put back on base, turn to 25#, lift kettle and re-add the 10# weight and put the kettle back on base. Use as normal