Motor Jittering

In Starstruck I just changed to HS motors on the lift with 1:7 gear ratio. But when we pick up 5 stars the lift goes up then stops and jitters we are using a rubber band assist. I can’t identify the problem I have but I have checked and the motors are spinning the right direction and there is no excessive friction and the motors are completely cooled. What I think is the problem: the motors are drawing too much power. Your help is much appreciated

Nevermind I found the solution here