Agree with Tommy. There should be certain conditions that keep the drive in low speed - boom raised, or rotated past a certain point, not sure if they would have put a reduced speed if battery voltage is low, but somewhere in the operators manual, there should be info, but you might have to read the whole thing. Genie has all manuals online - get your serial number and look at genielift.com go to support tab, then manuals on drop down list, then z-booms etc.. Toward the end of the service and repair manual you can normally find diagrams if you are able to use them. If your not able to read them you may find yourself throwing parts at it. I might be able to help you more, but would probably need to be able to get some pictures and be able to communicate on the phone. Definetly would need serial number. If you try to call genie, you will probably hold a very long time to find that they will not help you without and account and if the machine is over 10 years old - $75 for first call then $99 per hour after that - if you have an account.