DIAGNOSIS The heat is too high. Once pressure is reached, you need to reduce the heat significantly to maintain a steady, low pressure that lets the regulator rock gently. A violent, sputtering rattle means it's on full blast.
FIX As soon as the regulator starts rattling (indicating pressure is building), immediately turn your burner down to low or medium-low. On an induction cooker, you might need to go down to power level 3 or 4. It can take a minute or two for the internal pressure to stabilize and for the rocking to become slow and steady (about 1-3 rocks per minute).
IF THAT DIDN'T WORK If you've turned the heat way down and it's still going nuts, check that the vent pipe underneath the weight is completely clear. Unplugged it with a toothpick. A partially blocked vent can cause erratic pressure release. Also, ensure you're using enough liquid—if the pot is too dry, pressure can't build consistently.
HEADS UP Cooking at this violently high pressure isn't safe—it dramatically increases the chance of the safety vent blowing or food clogging the vents. It also evaporates your cooking liquid too fast, which can lead to burning. Low and slow once it's pressurized is the rule.