i know its been a while since this post and nobody answered it
but i thought it would be wise to come and at least make a comment.
I assume you have gotten this issue resolved in whatever manner you did but.....
word of caution when it comes to altering a boom or sissorlift out of its origional design without prior consent by the manufacturer...
YOU assume the responsibility of safety and void any warranty or mfg responsibility when doing so.
What you should have done at the point when the dealer told you they didnt know the information you seeked? Call genie technical support for help. All of thier information is publically listed on thier website and what isnt published there they will gladly help you if you call their technical support engineers. Their contact information is on thier site as well. They are very curteous and helpful and would of gladly helped you resolve this issue.

Just FYI.....for anyone that is thinking about altering any machine of this type no matter who the mfg is. There are serious ramifications that could result from altering these machines if a safety situation would happen to occur.